Republican Sen. Susan Collins of Maine broke party ranks Monday by voting against Justice Amy Coney Barrett’s confirmation. The move comes as Collins faces a tough reelection battle against Democratic Maine House Speaker Sara Gideon.

Collins, who has long been considered a moderate in a state that leans blue, was the sole Republican defector while all Democrats voted against Barrett. Barrett was confirmed by the Senate, 52-48.

Collins' vote against Barrett may be considered a last-ditch effort to win over moderates.

“Prior to Justice Ruth Bader Ginsburg’s death, I stated that, should a vacancy on the Supreme Court arise, the Senate should follow the precedent set four years ago and not vote on a nominee prior to the presidential election,” Collins said in a statement Sunday. “Because this vote is occurring prior to the election, I will vote against the nomination of Judge Amy Coney Barrett.”

There has been special attention paid to Collins in recent years. Collins’ vote to confirm Justice Brett Kavanaugh in October 2018 made her a major target of Democrats helping Gideon surpass Collins in campaign contributions.

Recent polls show a close race in the state, with the Cook Political Report rating it a "toss up." Gideon leads Collins by 4 points in the Real Clear Politics polling average.

There also have been concerns about Collins' voting record on women's rights. Though Collins supports Roe vs. Wade, Gideon has frequently attacked Collins over her choice to confirm Kavanaugh. Both Kavanaugh and Barrett are considered a threat to overturn Roe vs. Wade.

Kavanaugh was accused of sexual assault in high school by Christine Blasey Ford, now a psychology professor at Palo Alto University in California. Kavanaugh denied the allegations.

Collins, who faces her most difficult test to retain her seat, has served as Maine’s senator since 1997. Polls in Maine show Democratic nominee Joe Biden with a large lead on President Donald Trump.