WASHINGTON — House Democrats launched into marathon arguments in President Donald Trump’s impeachment trial Wednesday, appealing to skeptical Republican senators to join them in voting to oust Trump from office to “protect our democracy.”

Trump’s lawyers sat by, waiting their turn, as the president blasted the proceedings from afar, threatening jokingly to face off with the Democrats by coming to “sit right in the front row and stare at their corrupt faces.”

The challenge before the House managers is clear. Democrats have 24 hours over three days to prosecute the charges against Trump, trying to win over not just fidgety senators sitting silently in the chamber but an American public, deeply divided over the president and his impeachment in an election year.

Rep. Adam Schiff, chairman of the House Intelligence Committee, outlined what the Democrats contend was the president’s “corrupt scheme” to abuse his presidential power and then obstruct Congress’ investigation. He then called on senators not to be “cynical” about politics, but to draw on the intent of the nation’s Founding Fathers who provided the remedy of impeachment.

“Over the coming days, we will present to you—and to the American people—the extensive evidence collected during the House’s impeachment inquiry into the president’s abuse of power,” said Schiff standing before the Senate. “You will hear their testimony at the same time as the American people. That is, if you will allow it.”

After a dinner break, Schiff returned to the well of the Senate to detail the administration’s hold on military aid to Ukraine. He played several clips of testimony from Ambassador William Taylor, who said the assistance was held back as Trump pushed the country to announce investigations of Democrats.

Most senators sat at their desks throughout, as the rules stipulate, though some stretched their legs, standing behind the desks or against the back wall of the chamber, passing the time.

The proceedings are unfolding at the start of an election year, and there are few signs that Republicans are interested in calling more witnesses or going beyond a fast-track assessment that is likely to bring a quick vote on charges related to Trump’s dealings with Ukraine.

Several GOP senators said Wednesday they’d seen no evidence to support the allegations against Trump even though, just 24 hours earlier, they had rejected subpoenas for witnesses and documents. Democrats, meanwhile, described the evidence against the president as overwhelming but said senators have a duty to gather more.

A new poll from The Associated Press-NORC Center for Public Affairs Research shows the public is slightly more likely to say the Senate should convict and remove Trump from office than to say it should not, 45% to 40%. But a sizable percentage, 14%, say they don’t know enough to have an opinion.

One question there’s wide agreement on: Trump should allow top aides to appear as witnesses at the trial. About 7 in 10 said so, including majorities of Republicans and Democrats, according to the poll.