Sen. Susan Collins, the centrist Maine Republican who voted to extend the impeachment trial by calling for new witnesses, announced she will vote "no" on the two articles of impeachment against President Trump.

Collins on Tuesday announced her decision in a Senate floor speech hours before Trump is scheduled to deliver his State of the Union address to lawmakers.

She said the House impeachment case did not meet the "high bar" for removing Trump from office.

"I do not believe the House has met its burden," Colllins said.

She cited the "traumatic impact" of removing the president and said doing so would act against the will of the people. Collins also raised a July 25 phone call between Trump and Ukraine's president. While Collins said the conversation "demonstrated very poor judgment," she concluded there was conflicting information about the president's motives in the call.

Collins is one of two Republicans who voted to extend the trial. She voted to acquit President Bill Clinton of two impeachment charges in 1999, going against most in her party.

The other, Sen. Mitt Romney of Utah, has yet to announce his decision, but he's been critical of Trump’s decision to press Ukraine to investigate former Vice President Joe Biden, an action that is at the heart of the impeachment charges against him.

[ Also read: Susan Collins receives threatening messages ahead of impeachment witness vote]

Senate Republicans are poised to acquit Trump Wednesday on two articles of impeachment charging him with abuse of power and obstruction of Congress.

It takes 67 votes to convict the president, and Republicans control 53 votes.

Senate Majority Leader Mitch McConnell, a Kentucky Republican, in a Tuesday morning floor speech called on all senators to acquit the president of the charges.

Both parties are hoping to hold their senators in line on what is likely to be a mostly party-line vote Wednesday.

Senate Minority Leader Chuck Schumer, a New York Democrat, will not indicate whether any Democrats will vote to acquit the president.

Sen. Joe Manchin of West Virginia said Monday that the Senate should censure Trump. Sens. Doug Jones of Alabama and Kyrsten Sinema of Arizona may also vote to acquit the president.

"I think each Democrat is going to make up his or her own mind,” Schumer said. “This is an issue of conscience to everybody."