Sen. Joe Donnelly (D-IN), who faces a tough reelection battle this cycle, on Friday announced his decision to vote against Brett Kavanaugh's appointment to the Supreme Court.

“I have deep reservations about Judge Kavanaugh's nomination to this lifetime position and, as I stated, we have been unable to get all the information necessary regarding this nomination, despite my best efforts,” wrote Donnelly, who voted to confirm Trump-appointed Justice Neil Gorsuch, in a statement. “Only 113 people have ever served on the Supreme Court, and I believe that we must do our level best to protect its sanctity.” He added: “While I would gladly welcome the opportunity to work with President Trump on a new nominee for this critically important position, if Judge Kavanaugh’s nomination comes before the full Senate vote under these circumstances, I will oppose it.”

Donnelly was viewed as a key swing vote in the Kavanaugh confirmation process. He joins red-state Democrats Sen. Claire McCaskill (D-MO) and Sen. Bill Nelson (D-FL), both running for reelection this year, in opposition to the Trump appointee.

Sens. Joe Manchin (D-WV) and Heidi Heitkamp (D-ND), meanwhile, have yet to announce their decisions. On the Republican side, Sens. Susan Collins (R-ME) and Lisa Murkowski (R-AK) are similarly undecided. Earlier on Friday, Sen. Jeff Flake (R-AZ) announced that he would support the Kavanaugh pick.