Sen. Mark Warner delivers remarks during a Rules Committee hearing at the Russell Senate Office Building on November 14, 2023, in Washington, DC.
CNN  — 

An effort is underway by Virginia Sen. Mark Warner to get Senate Democrats on the same page about the future of President Joe Biden’s reelection bid, sources told CNN, putting further pressure on the White House as it struggles to handle questions about the president’s mental fitness and the viability of his campaign.

Warner, who is taking on a leadership role in the effort, is reaching a place where he thinks it is time for Biden to suspend his reelection campaign, a source familiar with his efforts told CNN.

The Biden administration and campaign have grappled in recent days with how to spin the president’s poor debate performance, offering contradicting excuses and making the argument that Biden’s record in the past three years is more significant than his shaky 90-minute standoff with former President Donald Trump.

However, the debate only exacerbated concerns about the president’s health and questions on whether he is fit to serve another four years in office. As pressure has increased within the party, some Democrats have urged the president to consider whether he is the party’s best chance at beating Trump in November, while others have gone as far as to call for him to step aside as their presumptive nominee.

Warner’s meeting with his colleagues, first reported by The Washington Post, is expected to take place Monday, according to a source familiar with the planning.

Biden responded to reports of Warner’s efforts on Friday, telling ABC News’ George Stephanopoulos in an interview that “Mark is a good man” but he has a “different perspective.”

“Well, Mark is a good man. We’ve never had that. He also tried to get the nomination too. Mark’s not, Mark and I have a different perspective. I respect him,” he said without elaborating, adding that members of Democratic congressional leadership have told him to “stay in the race.”

Warner declined CNN’s request for comment. His spokeswoman, Rachel Cohen, neither confirmed nor denied the senator’s efforts in a statement to the Post earlier Friday, saying: “Like many other people in Washington and across the country, Senator Warner believes these are critical days for the president’s campaign, and he has made that clear to the White House.”

Meanwhile, House Minority Leader Hakeem Jeffries is summoning his members to a virtual meeting Sunday with Democratic committee ranking members, which is expected to focus on Biden, a Democratic lawmaker told CNN.

Jeffries’ meeting was first reported by NBC News.

Biden privately told an ally earlier this week that the next stretch of days is critical to whether he can save his reelection bid. But the president remained defiant Friday, telling reporters before boarding Air Force One following a campaign rally in Wisconsin that he is “completely ruling out” getting out of the 2024 race.

This story has been updated with additional details.

CNN’s Samantha Waldenberg contributed to this reporting.