Sen. Susan Collins, R-Maine, said Wednesday she'll be seeking reelection, in an announcement ahead of the Senate's expected trial of President Trump.

Collins has maintained she's willing to have an open mind when considering articles of impeachment against the president. The center-leaning senator famously gave a last-minute speech in support of Brett Kavanaugh for the Supreme Court last year ahead of the Senate's narrow vote to confirm the justice.

Although she hasn't publicly weighed in on whether or not she would vote for or against removing the president, Collins repeatedly has defended the whistleblower whose allegations of misconduct by Trump have been central to the investigation into the president's abuse of power and obstruction of Congress.

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The last remaining New England Republican in Congress, Collins historically has presented herself as a moderate politician, bucking party-line stances on issues such as abortion and challenging Trump's policies, including building a wall on the southern border between the U.S. and Mexico and withdrawing troops from Syria.

In this Nov. 6, 2019, file photo, Sen. Susan Collins, R-Maine, is surrounded by reporters as she heads to vote at the Capitol in Washington. Collins officially launched her bid for a reelection Wednesday, Dec. 18, setting up an expensive and closely watched battle for the seat the moderate Republican from Maine has held for nearly 24 years. (AP Photo/J. Scott Applewhite, File)

Collins detractors from the left have slammed her for supporting Kavanaugh for the Supreme Court, despite a myriad of sexual misconduct allegations against him, as well as advocating for the GOP tax cut.

"The fundamental question I had to ask myself in making my decision was this: In today's polarized political environment, is there still a role for a centrist who believes in getting things done through compromise, collegiality, and bipartisanship?" Collins said in an email, according to reports by NPR. "I have concluded that the answer to this question is 'yes' and I will, therefore, seek the honor of continuing to serve as Maine's United States senator."

Four Democrats are vying for the party’s nomination to face the 67-year-old senator, include activist Betsy Sweet, attorney Bre Kidman, former Google executive Ross LaJeunesse and Maine House Speaker Sara Gideon, who is backed by the Democratic Senatorial Campaign Committee.

Collins has amassed $8.6 million for her reelection bid, the largest haul of any political candidate in Maine history.

The expensive race is projected to cost anywhere between $80 million to $100 million before the 2020 elections, making it the most expensive run the state has ever seen.

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The Associated Press contributed to this report.