Ahead of a potentially pivotal week on Capitol Hill, the Biden-Harris campaign is stepping up its outreach to lawmakers amid growing calls for President Biden to step down from the ticket. Mr. Biden has personally made 20 calls to congressional members since last month's presidential debate in Atlanta and additional calls are expected, a campaign official confirms to CBS News. 

Last week, the White House said the president spoke with several key allies including Senate Majority Leader Chuck Schumer, House Minority Leader Hakeem Jeffries, Speaker Emerita Nancy Pelosi, Rep. Jim Clyburn of South Carolina and Sen. Chris Coons of Delaware. Vermont Senator Bernie Sanders also told Face The Nation Sunday that he had recently spoken with the president.

A memo acquired by CBS News, which was sent to Hill offices by the Biden-Harris campaign, highlights more than a dozen appearances by the president since the debate in "blue wall states," including this weekend's campaign events in Wisconsin and Pennsylvania. On Sunday, Mr. Biden spoke at a Philadelphia church, stopped by a field office with Sen. John Fetterman of Pennsylvania to rally volunteers and joined Pennsylvania Gov. Josh Shapiro at a coffee shop in Harrisburg. 

"I'm up to the job," Biden, 81, told reporters before departing the Keystone State on Air Force One.

The memo outlines Mr. Biden's upcoming schedule this week, which features the NATO summit, a meeting with union leaders at the AFL-CIO Wednesday and a campaign event in Detroit Friday. It points to a new Bloomberg/Morning Consult poll that shows Mr. Biden narrowing the gap to 45%-47% against former President Donald Trump in seven key battleground states. It also boasts support from surrogates and grassroots donors, citing June as its "best" fundraising month with a $127 million haul.

"Since the debate, we've seen an outpouring of robust and continually growing grassroots support, sending a clear message – Americans understand the stakes and are fired-up and ready to re-elect Joe Biden and Kamala Harris," the memo reads.

The effort follows a Sunday afternoon leadership call with ranking members from various House committees. Several senior House Democrats said the President should end his re-election campaign in the wake of his recent debate performance, multiple people tell CBS News.

At least five House Democrats have called on the president to step down as the party nominee. Virginia Sen. Mark Warner scrapped a Monday meeting with a group of Senate Democrats to discuss the president's bid, a source familiar with the senator's thinking confirmed to CBS News. 

House and Senate Democrats are expected to hold separate meetings Tuesday where Mr. Biden's embattled presidential campaign is likely to come up. 

"I've got a wait and see position to see how things go," one House Democrat told CBS News. "I think most people just want to continue to see how the president does."

-- additional reporting by Nancy Cordes.

In:
• Joe Biden