The Senate is certain to acquit President Trump as his impeachment trial wraps up Wednesday — but Republicans and Democrats still spent much of the day Tuesday arguing over whether he should be booted from office.

Sen. Susan Collins of Maine, one of two Republicans who sided with Democrats about calling witnesses, and who called Trump wrong for asking Ukraine’s president to probe Joe and Hunter Biden — said she would vote to acquit him anyway.

“It was wrong for President Trump to mention former Vice President Biden on that phone call, and it was wrong for him to ask a foreign country to investigate a political rival,” Collins said.

“While I do not believe that the conviction of a president requires a criminal act, the high bar for removal from office is perhaps even higher when impeachment is for a difficult-to-define noncriminal act,” she said.

Senate Majority Leader Mitch McConnell urged his fellow senators to acquit Trump, warning that the fate of the republic depended on it, even as his Democratic counterpart called Trump a threat to democracy.

The partisan rancor in the dueling speeches by the Senate’s top Republican and Minority Leader Chuck Schumer (D-NY) underscored the polarization in the country over Trump’s ­impeachment.

McConnell urged the Senate to stop what he called the Democrats’ “abuse of power” in impeaching Trump in the House.

“We must vote to reject the House abuse of power, vote to protect our institutions, vote to reject new precedents that would reduce the framers’ design to rubble, vote to keep factional fever from boiling over and scorching our republic,” McConnell (R-Ky.) said.

“Washington Democrats think President Donald Trump committed a high crime or misdemeanor the moment — the moment — he defeated Hillary Clinton in the 2016 election,” he continued.

“That is the original sin of this presidency — that he won and they lost,” McConnell said.

Schumer countered: “The administration, its top people and Senate Republicans are all hiding the truth. The charges are extremely serious. To interfere in an election, to blackmail a foreign country, to interfere in our elections gets at the very core of what our democracy is about.”

Meanwhile, Sen. Ed Markey (D-Mass.) said that if Republicans acquit Trump, “A majority in this chamber will have made President Trump a dictator.”

Sen. Gary Peters (D-Mich.), running for re-election in a state Trump won in 2016, said he would vote to convict, saying the facts were clear.

“By refusing to hold President Trump accountable for his abuses, Republicans in the Senate are offering him unbridled power without accountability and he will gleefully seize that power,” Peters said.

The House impeached Trump on Dec. 18 on charges of abuse of power and obstruction of Congress. The first charge is tied to Trump asking Ukraine President Volodymyr Zelensky to announce an investigation into the Bidens — over Hunter’s high-paying position on the board of a Ukraine energy company while Joe was vice president — at a time when Trump was withholding aid to Ukraine. The second charge was for blocking testimony and documents sought in the impeachment probe.

Trump has denied any linkage between the Biden request and holding the aid, which he ultimately released in September.

A two-thirds vote is needed in the Senate to remove Trump from office and his fellow Republicans occupy 53 of the 100 seats.