Speaker Nancy Pelosi (D-Calif.) said Friday that President Trump's attempts to sow doubts about mail-in ballots amounted to a "domestic assault on our Constitution."

"We take an oath of office to protect and defend the Constitution from all enemies, foreign and domestic. The actions this administration are taking vis-a-vis our voting system, our sacred right to vote, are a domestic assault on our Constitution," Pelosi said in an interview on MSNBC.

Pelosi encouraged Americans choosing to vote by mail instead of risking potential exposure at a polling place to cast their ballots sooner rather than later.

"Don't risk your health, vote by mail. But if you do, vote plenty early because within this administration is an attempt to make sure your vote doesn't count and doesn't count as cast," Pelosi said.

Trump has repeatedly claimed, without evidence, that voting by mail is more likely to result in widespread fraud on Election Day.

On Thursday, the president initially indicated that he was opposed to giving the U.S. Postal Service (USPS) emergency funding to handle the expected increase in mailed ballots during the COVID-19 pandemic. But later that day, he said he would be willing to sign legislation that includes USPS funding but rejected reversing new agency policies slowing mail delivery that Democratic lawmakers have warned could make it more difficult to process ballots in November.

"I want the post office to run properly, which makes sense. They would need a lot more money if they’re going to be taking in tens of millions of ballots that just come out of the sky from nowhere," Trump said at a White House press conference.

That position contrasted with earlier remarks from a Fox Business interview in which Trump indicated opposition to providing funding as a way to prevent universal mail-in voting.

"They want $25 billion for the post office. Now, they need that money in order to have the post office work so it can take all of these millions and millions of ballots," Trump said. "Now in the meantime, they aren't getting there. By the way, those are just two items. But if they don't get those two items that means you can't have universal mail-in voting, because they're not equipped to have it."

Trump and first lady Melania Trump have both requested mail-in ballots for the upcoming congressional primaries in Florida. Trump also voted by mail in the state's presidential primary in March.

House Democrats passed a $3 trillion coronavirus aid package in May that included $25 billion for the USPS, which Pelosi said was an amount recommended by the Postal Service's board of governors. The GOP-controlled Senate declined to take up that bill.

Pelosi on Friday also discussed the stalled negotiations between congressional Democrats and Trump administration officials on another coronavirus relief package.

The Speaker downplayed the idea that the stalemate could result in backlash against House Democrats representing swing districts, some of whom have expressed concern that congressional leaders will fail to reach any deal.

"Overwhelmingly, the House Democratic Caucus, including our freshmen, very much want us to meet the needs of the American people. There may be a few who are new to all of this, but by and large we are very proud of the leverage that the House Democratic caucus is giving me as well as the Senate caucus to Leader Schumer," Pelosi said, referring to Senate Minority Leader Charles Schumer (D-N.Y.).

"By and large, our caucuses say we have to do what is right for the American people," she added.