Supreme Court nominee Brett Kavanaugh broke a political firewall Monday afternoon by meeting with West Virginia Sen. Joe Manchin -- the first Democrat to sit down with President Trump's pick for the high court.

The Manchin meeting could set the stage for other swing-vote Democrats to talk with Kavanaugh or even support him, despite fierce pressure from party leaders and activists.

Manchin said earlier this month that Senate Minority Leader Chuck Schumer, D-N.Y. can "kiss my you-know-what" if he tries to pressure the West Virginia Democrat into opposing Kavanaugh. Manchin is facing a tough re-election battle in a state that went for Trump by double-digits in 2016.

In a statement to Fox News, Manchin's Republican challenger, West Virginia Attorney General Patrick Morrisey, accused Manchin of making a "craven political calculation" by delaying his decision on Kavanaugh's nomination until "the outcome has already been decided."

"Sen. Manchin needs to quit waffling and support President Trump's Supreme Court nominee," Morrisey said. "Clearly, Sen. Manchin is holding out his support for Judge Kavanaugh in order to assist liberal Chuck Schumer’s obstructionism."

Manchin's office released photographs of Kavanaugh talking and smiling with the senator late Monday.

The senator has said he's interested in Kavanaugh's views on the Affordable Care Act and its protections for people with pre-existing conditions. He has also asked his constituents to send him questions for the meeting.

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After Manchin said he would talk with Kavanaugh, another red-state Democrat, Sen. Joe Donnelly, D-Ind., last week announced he also would meet with Kavanaugh. That sit-down is scheduled for Aug. 15.

Manchin was one of three Democrats who voted to confirm Trump's first Supreme Court nominee, Neil Gorsuch. Donnelly and Sen. Heidi Heitkamp of North Dakota were the others. All three are up for re-election in states Trump easily won in 2016.

Manchin has said he regrets backing Hillary Clinton in 2016, and hinted that he could support President Trump’s re-election in 2020.

With the absence of Sen. John McCain, R-Ariz., who is fighting brain cancer, Republicans cannot afford to lose a single GOP vote to confirm Kavanaugh if all Democrats vote "no." Only a simple majority is needed to confirm Kavanaugh, after Republicans eliminated the filibuster for Supreme Court nominees last year. Democrats had previously eliminated the filibuster for other judicial nominees under the Obama administration.

There were new signs early Monday that Republicans were falling in line to support the nominee. Sen. Rand Paul announced after he met with Kavanaugh that he would support the nominee, despite earlier voicing reservations about Kavanaugh's commitment to privacy rights.

The Kentucky senator was one of the few Republicans considered possible swing votes on Kavanaugh's confirmation. Sens. Susan Collins, R-Maine, and Lisa Murkowski, R-Alaska, who voted to confirm Gorsuch last year, also are being watched closely.

Both senators support abortion rights, and liberal advocacy groups have argued that Kavanaugh's confirmation would undermine Roe v. Wade, the 1973 Supreme Court decision.

But with Paul voicing clear support -- and Collins and Murkowski signaling potential support in recent weeks -- Kavanaugh's prospects appear to be improving as GOP leaders aim to engineer a swift confirmation by the fall.

Fox News' Judson Berger and The Associated Press contributed to this report.