<a href="https://abcnews.go.com/Politics/timeline-years-political-fight-postal-service/story?id=72496712" target="_blank" rel="noopener noreferrer">Timeline: This year’s political fight over the Postal Service</a>  <font color="#6f6f6f">ABC News</font>

The potent mix of a history-defining presidential election and a world-altering pandemic has turned even America’s mail system into a political lightning rod.

The embattled head of the U.S. Postal Service, Postmaster General Louis DeJoy, is set to testify Friday before a Senate panel, marking his first public appearance since being accused of using the Postal Service to help boost President Donald Trump’s reelection bid.

Democrats are expected to press him over Trump’s own attacks on the Postal Service, including unfounded claims that the agency is ill-equipped to prevent widespread election fraud if millions of -wary voters choose to cast their ballots via mail in November.

Trump has taken sharp aim at “mail-in voting,” which – according to him – takes place when states proactively send ballots to registered voters. He insists that system is different and far more problematic than “absentee voting,” when –according to his distinction – voters request ballots be sent to them.

But whether it’s “mail-in voting” or “absentee voting,” most ballots are returned through the mail, and states have established safeguards to help verify that each voter is eligible to vote and casts only one ballot.

Experts warn, however, that when the Postal Service is slowed, some ballots could be delivered after key deadlines, rendering them invalid – so voters should request and return ballots early.

How did we get here? Here is a timeline of what’s unfolded so far this year:

January: The U.S. Postal Service continued to face significant financial losses and criticism from Trump, who repeatedly called on the agency to charge higher fees to companies like Amazon, which owns the Washington Post and whose owner Jeff Bezos has a fraught relationship with Trump.

The growing COVID-19 pandemic caused a steep decline in mail, dealing another major financial blow to the Postal Service. House Democrats unsuccessfully tried to provide the agency with tens of billions of dollars in emergency relief. Instead, Congress approved a $10 billion loan to the agency, which critics said would only push the agency further into debt.

By late March: As the COVID-19 pandemic spread across America, questions mounted over how voters could safely cast ballots in primary elections and then in the general election in November. Many states began looking for ways to expand their vote-by-mail capacity.

March 30: Speaking to Fox News, Trump indicated that he believes increasing ballot access nationwide would help Democrats. Criticizing Democratic proposals for a major pandemic relief bill, Trump said: “The things they had in there were crazy. They had levels of voting that if you ever agreed to it, you’d never have a Republican elected in this country again.”

March 31: Appearing on MSNBC, House Speaker Nancy Pelosi, D-Calif., said the country needed to prepare for “vote by mail,” including by providing emergency funding to the Postal Service so it could place equipment “where it needs to be.”

April 7: Trump renewed his calls for the Postal Service to raise its prices for companies like Amazon, saying, “We’re looking into it, and we’ve been pushing them now for over a year.”

April 8: Trump tweeted: “Republicans should fight very hard when it comes to state wide mail-in voting. … Tremendous potential for voter fraud, and for whatever reason, doesn’t work out well for Republicans.”

April 9: The outgoing head of the Postal Service, Postmaster General Megan Brennan, told a House panel that – after losing $13 billion due to the pandemic – the Postal Service will “run out of cash this fiscal year” without help from Congress and the Trump administration. She asked for $25 billion in emergency funds and another $25 billion to modernize the Postal Service.

April 24: While signing a pandemic stimulus bill at the White House, Trump said, “The Postal Service is a joke,” claiming agency officials won’t charge Amazon more because they are “cozy” with the company and “don’t want to insult Amazon.” Trump warned that if the Postal Service doesn’t raise prices on Amazon, “I’m not signing anything and I’m not authorizing [the Treasury Department] to do anything.”

Late April: A member of the board of governors, David C. Williams, resigned, reportedly over concerns that the Postal Service was being improperly politicized.

May 6: The board of governors announced that Louis DeJoy, a businessman who helped raise funds for Republicans and donated more than $1.2 million to the Trump Victory Fund, would replace Brennan as the new postmaster general.

May 29: The Postal Service issued a letter to state and local elections officials, telling them to account for “the Postal Service’s delivery standards” when “informing voters how to successfully participate in an election using the mail.” In particular, the letter said, “mail processing times need to be considered when communicating deadlines,” and “voters should mail their ballots at least one week prior to [their state’s] due date.”

June 15: DeJoy was sworn-in as postmaster general.

June 29: Concerned about a plan in Pennsylvania to set up drop-boxes across the state for voters to return their ballots in the November election, Trump’s reelection campaign and the Republican National Committee filed a federal lawsuit seeking to block the effort, claiming the drop-boxes “enhance[ ] the threat that fraudulent or otherwise ineligible ballots will be cast and counted.”

Mid-July: The Postal Service began implementing an “operational pivot,” prohibiting overtime pay, limiting certain operations, and telling employees in one memo to take the “not typical” action of leaving mail at distribution centers for another day if they are behind schedule. (The memo was obtained by The Washington Post.)

Late July: The Postal Service issued another round of letters to state elections officials, warning at least 40 states that their “deadlines for requesting and casting Mail-In ballots are incongruous with the Postal Service’s delivery standards.”

July 30: The Washington Post reported that, in the wake of the latest internal changes, the Postal Service was “experiencing days-long backlogs of mail across the country,” and that workers worried “the policies could undermine their ability to deliver ballots on time for the November election.” Democrats on Capitol Hill cried foul, framing the agency’s changes as an effort to disenfranchise voters.

July 30: Trump tweeted: “With Universal Mail-In Voting (not Absentee Voting, which is good), 2020 will be the most INACCURATE & FRAUDULENT Election in History. It will be a great embarrassment to the USA. Delay the Election until people can properly, security and safely vote???”

July 31: Under increasing pressure, the White House issued a statement saying any suggestion that Trump sought to slow mail delivery “is baseless and absurd.” Instead, the White House said, Trump is “demanding much needed and long overdue change.” DeJoy later issued a similar denial, saying that while his agency was “at the beginning of a transformative process,” no decisions would be made “based on partisanship.”

Aug. 3: Two months after voting sites in Nevada were plagued with long lines during the presidential primaries, the state’s governor signed into law a bill requiring that mail-in ballots be sent to all registered voters during states of emergency, such as the COVID-19 pandemic.

Aug. 4: Trump’s reelection campaign and the Republican National Committee filed a federal lawsuit against Nevada elections officials, seeking to block the law from being implemented. In their lawsuit, the campaign and RNC alleged that the new law would make “voter fraud and other ineligible voting inevitable.”

Aug. 5: Noting on Fox News that “we’re in court” against Nevada, Trump said the Postal Service is “not equipped to handle” the millions of ballots that could be mailed for the November election. (The agency handles more than 180 billion pieces of mail each year.)

Aug. 7: The Washington Post reported that DeJoy had “reassigned or displaced” 23 postal executives, including the two executives overseeing day-to-day operations.

Aug. 10: Warning against “a rigged election,” Trump insisted during a press conference that “mail-in voting” is “very susceptible.” “Our system is not equipped for it, the Post Office is not equipped for it, and people should vote like they did in World War I and World War II,” he said.

Aug. 12: Speaking at the White House, Trump criticized Democratic lawmakers who were seeking $25 billion for the Postal Service “so the Post Office can handle this vast amount of ballots.” He praised DeJoy as “a great person, a great businessman.”

Aug. 13: Appearing on Fox Business Network, Trump conceded that Democrats “need that money in order to make the Post Office work.” So, the president said, “if they don’t get those [funds] that means you can’t have universal mail-in voting.” He called the issue “one of the sticking points” in negotiations over a much larger pandemic relief bill. “If we don’t make a deal … that means they can’t have universal mail-in voting,” he said. At a press conference the same day, Trump said “mail-in voting” was “a system riddled by fraud and corruption,” but that “absentee ballots are fine.”

Aug. 13: Republican Sen. Susan Collins, R-Maine, sent a letter to DeJoy, urging him to “promptly address the delays in mail delivery that have occurred following recent operational changes.” Noting that he “still has not detailed to the public” the changes being made, Collins said “the goal of putting the USPS back on a financially sustainable path … cannot be achieved by shortchanging service to the public.”

Aug. 13: Local news outlets in Oregon, Montana and other states reported that – in light of Trump’s recent comments – some area residents were concerned after seeing Postal Service mailboxes being removed from neighborhood streets. An agency spokesman said the actions were part of a “routine” effort to remove “redundant/seldom used collection boxes,” especially with a decline in mail volume, but Democratic lawmakers questioned whether the actions were politically motivated.

Mid-August: Local and national news reports alleged that mail-sorting machines were being shut down – even taken apart – at Postal Service facilities across the country. The Washington Post reported that the Postal Service had decided to “decommission” 10 percent of its sorting machines. (It remains unclear why sorting machines would be removed.)

Aug. 16: The Postal Service announced that it was halting the removal of collection boxes until after the election, saying in a statement, “Given the recent customer concerns the Postal Service will postpone removing boxes for a period of 90 days while we evaluate our customers concerns.”

Aug. 17: A group of Democratic state attorneys general announced that they would be filing a federal lawsuit against the Trump administration over the Postal Service’s recent changes. (The lawsuit was filed the next day, alleging the Postal Service’s changes violate voters’ constitutional rights, failed to follow proper procedures, and should be blocked.) In response, the White House said any such “politically motivated lawsuits are not rooted in giving Americans the power of the vote.”

Aug. 18: DeJoy issued a public statement, saying, “To avoid even the appearance of any impact on election mail, I am suspending [the new] initiatives until after the election is concluded.” He said he wants to “assure all Americans” that retail hours “will not change,” “mail processing equipment and blue collection boxes will remain where they are,” and that over time will be “approved as needed.” “The Postal Service is ready today to handle whatever volume of election mail it receives this fall,” he insisted. The statement did not say whether changes already made would be reversed, and news reports since his statement have highlighted more alleged instances of decommissioned sorting machines.

Aug. 19: DeJoy spoke with Pelosi about the latest developments. According to Pelosi’s account of the conversation, DeJoy “frankly admitted that he had no intention of replacing the sorting machines, blue mailboxes and other key mail infrastructure that have been removed and that plans for adequate overtime … are not in the works.” Pelosi said the “damage [was] already wreaked.”

ABC News’ Lucien Bruggeman, Devin Dwyer, Ben Gittleson and Marilyn Heck contributed to this report.