Sen. Susan Collins (R-ME) said on Tuesday that “it’ll be very difficult for anyone to argue” that Supreme Court nominee Brett Kavanaugh “is not qualified.”

President Donald Trump nominated District of Columbia Circuit Court of Appeals Judge Kavanaugh to the Supreme Court on Monday.

Collins said on Tuesday, “It’ll be very difficult for anyone to argue he’s not qualified.”

The Maine senator also said she will consider his “judicial temperament” and “judicial philosophy.”

Senate Republicans face a slim majority of 51-49 in the Senate, making any nomination to the Supreme Court a contentious battle. Republicans can only afford to lose one vote in the Senate and have Vice President Mike Pence break the tie unless red state Democrats back the president’s nominee.

Last week, Sen. Collins voiced concerns regarding Trump’s potential nominee, signaling she would not vote to confirm any judge who might overturn Roe v. Wade.

Collins said on CNN’s State of the Union, “I would not support a nominee who demonstrated hostility to Roe v. Wade. She added that Roe established abortion as a “constitutional right.”

On ABC News’s This Week, Collins said any judge who would like to overturn Roe has an “activist agenda,” which violates the fundamental tenets of the Constitution.

After President Trump’s nomination of Kavanaugh on Monday, Collins said, “Judge Kavanaugh has impressive credentials and extensive experience, having served more than a decade on the D.C. Circuit Court of Appeals.”

“I will conduct a careful, thorough vetting of the President’s nominee to the Supreme Court, as I have done with the five previous Supreme Court Justices whom I have considered,” Collins continued.

Sen. Collins has bucked the Senate Republican conference in the past. She, along with Sens. Lisa Murkowski (R-AK) and John McCain (R-AZ), tanked Obamacare repeal twice and was one of the last holdouts to support Trump’s Tax Cuts and Jobs Act.

Several prominent Republican senators backed Kavanaugh on Monday night. Senate Majority Leader Mitch McConnell (R-KY) called Kavanaugh a “super choice,” Senate Majority Whip John Cornyn (R-TX) called the nominee an “exceptionally qualified jurist,” and Sen. Orrin Hatch (R-UT) said he “will lift heaven and earth to get Judge Brett Kavanaugh on the Supreme Court.”