The House of Representatives has charged Trump, a Republican, with inciting an insurrection by exhorting thousands of supporters to march on the Capitol on the day Congress was gathered to certify Democrat Joe Biden’s electoral victory.

The rioters stormed the building, sending lawmakers into hiding and leaving five people dead, including a police officer.

The nine Democratic House managers prosecuting the case for impeachment, an uphill task in an narrowly divided Senate, said on Wednesday the incitement started long before Jan. 6.

“Trump realized last spring that he could lose the November election and began planting seeds of anger among his supporters by saying he could lose only if it was stolen,” said Representative Joseph Neguse.

“If we are to protect our republic and prevent something like this from ever happening again, he must be convicted.”

Representative Joaquin Castro cited what he called blatant acts of political intimidation against election workers in states Trump was losing. In Philadelphia, Atlanta and Milwaukee, Castro said, Trump’s supporters tried to use armed force to disrupt the counting of votes.

“They believed it was their duty to quite literally fight to stop the count,” Castro said.

Trump’s actions threatened a hallmark of American democracy, the peaceful transfer of power, the Democratic managers said.

“This case is not about blaming an innocent bystander for the horrific violence and harm that took place on Jan. 6,” lead manager Jamie Raskin said as he opened the proceedings. “This is about holding accountable the person singularly responsible for inciting the attack.”

Democrats face long odds to secure a conviction, which could lead to a vote barring Trump from seeking public office again. A two-thirds majority in the Senate must vote to convict, which means at least 17 Republicans would have to defy Trump’s still-potent popularity among Republican voters.

Republican Senator Ron Johnson, a Trump ally, told reporters at a break that the proceedings would become “pretty tedious.”

“This is a political exercise,” he said.

On Tuesday, just six out of 50 Republican senators broke with their caucus to vote that the trial could move ahead even though Trump’s term ended on Jan. 20.

In an Ipsos poll for Reuters that was released on Wednesday, 47% of respondents said Trump should be convicted while 40% said he should not, with opinions split along party lines.

The trial in the Senate is not the only probe Trump faces after leaving the White House and losing the presidential protections that shielded him from prosecution.

Prosecutors in Georgia’s biggest county have opened a criminal investigation into Trump’s attempts to influence the state’s election results after he was recorded in a Jan. 2 phone call pressuring the Secretary of State to “find” enough votes to overturn his Georgia loss.