Sen. Joe Manchin Joseph (Joe) ManchinManchin defends Supreme Court candidate Barrett: 'It's awful to bring in religion' The Hill's Morning Report - Sponsored by Facebook - Trump, GOP allies prepare for SCOTUS nomination this week Trump meets with potential Supreme Court pick Amy Coney Barrett at White House MORE (D-W.Va.) said on Monday that he will back legislation to prevent the separation of immigrant families along the border, solidifying Democratic support for the bill.

Manchin's decision means all 49 members of the Democratic caucus, which includes independent Sens. Bernie Sanders Bernie SandersOutrage erupts over Breonna Taylor grand jury ruling Dimon: Wealth tax 'almost impossible to do' Grand jury charges no officers in Breonna Taylor death MORE (Vt.) and Angus King Angus KingGovernment watchdog recommends creation of White House cyber director position Democrats step up hardball tactics as Supreme Court fight heats up Shakespeare Theatre Company goes virtual for 'Will on the Hill...or Won't They?' MORE (Maine), are signing on to the legislation.

“As a father, grandfather, and Christian, I am wholeheartedly opposed to any policy that allows innocent children to be separated from their parents as they enter our country," Manchin said in a statement.

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"No law requires pulling children from the arms of their parents," he added.

The legislation, spearheaded by Democratic Sen. Dianne Feinstein Dianne Emiel FeinsteinFeinstein 'surprised and taken aback' by suggestion she's not up for Supreme Court fight Democrats shoot down talk of expanding Supreme Court Biden leads Trump by 12 points among Catholic voters: poll MORE (Calif.), would only allow children to be separated from a parent if they are being abused, trafficked or if a court decides "it is in the best interests of the child."

As of late last week, it had the support of 43 senators in the caucus. Five more red-state Democrats — Sens. Claire McCaskill Claire Conner McCaskillMomentum growing among Republicans for Supreme Court vote before Election Day Democratic-linked group runs ads in Kansas GOP Senate primary Trump mocked for low attendance at rally MORE (Mo.), Doug Jones (Ala.), Jon Tester Jonathan (Jon) TesterDemocrats shoot down talk of expanding Supreme Court Pence seeks to boost Daines in critical Montana Senate race This World Suicide Prevention Day, let's recommit to protecting the lives of our veterans MORE (Mont.), Joe Donnelly Joseph (Joe) Simon DonnellyHarris faces pivotal moment with Supreme Court battle Trump meets with potential Supreme Court pick Amy Coney Barrett at White House Names to watch as Trump picks Ginsburg replacement on Supreme Court MORE (Ind.) and Heidi Heitkamp Mary (Heidi) Kathryn HeitkampHarris faces pivotal moment with Supreme Court battle Centrists, progressives rally around Harris pick for VP 70 former senators propose bipartisan caucus for incumbents MORE (N.D.) — announced over the weekend they would sign on to the bill, leaving Manchin as the last remaining holdout.

Manchin, McCaskill, Tester, Donnelly and Heitkamp are running for states easily won by Trump during the 2016 election.

The Feinstein bill, however, faces an unlikely, uphill climb in a GOP-controlled Congress, despite growing backlash over the Trump administration's policies that are resulting in the separation of immigrant families at the border.

No Republican senator has said they will support Feinstein's bill, which would need 60 votes to clear the Senate.

Manchin added on Monday that the United States needs to "secure our borders and enforce our immigration laws" and that he's talking with GOP lawmakers about broader legislation.

"I am actively working with my Republican colleagues to find solutions to the issues that are not addressed" in Feinstein's bill, he said. "I continue to believe that the comprehensive 2013 immigration bill that included 700 miles of fencing, an addition 20,000 border control agents and other measures to secure our border is where we should begin this process."