"I don't think the choice of the next Senate leader is going to be based on any single vote. Members of the caucus respect Chuck and know he's gone through a thoughtful reflection. I don't think it has any impact on the leadership race," Senator Dick Durbin of Illinois told the Hill newspaper in an interview Tuesday.
Durbin, who is Schumer's former roommate in Washington and would be a likely candidate for the top post in his party, said he wasn't surprised his colleague came out against the deal.
"I can tell you that I know Chuck pretty well. I have listened to him carefully and heard his comments about the negotiations carefully," Durbin told the Hill. "I always expected him to be against the agreement. This didn't come as a major shock or surprise."
The current Senate Democratic Leader, Harry Reid of Nevada, announced his retirement in March and Schumer quickly locked up commitments from fellow Democrats to ascend to his post in January 2017.
When the news broke late last week that Schumer would vote to block the Iran deal, progressive Democrats and former Obama administration officials immediately began attacking him, and some argued he should no longer be in line to serve as the Senate Democratic leader.
But so far, not one Senate Democrat has publicly criticized Schumer's decision or suggested he or she would oppose his leadership bid.
After a speech in New York on Tuesday, Schumer said fellow Democrats understand where he stands and aren't telling him it will affect they're vote in the next leadership election.
"My colleagues -- and many of them have called me in the last few days -- everyone believes this is a vote of conscience. They respect my vote of conscience and I'll respect theirs, whichever way they come out," Schumer said.
Missouri Democratic Rep. Claire McCaskill also said Schumer's vote had no impact on the leadership race. Asked on MSNBC's "Morning Joe" if Schumer still has her vote, she replied, "Of course."
Multiple Senate Democratic sources also tell CNN that Schumer's concerns with the nuclear deal were well known by the White House and fellow Democrats and most expected him to vote against the agreement, so the public break with the White House wasn't a surprise.
One liberal grassroots group, Credo Action, started collecting signatures for an online petition with the headline: "Tell Sen. Chuck Schumer: Don't lead Senate Democrats into war with Iran."
This group and other progressives were critical of Schumer over his close ties with Wall Street when Reid announced his plans to step down earlier this year, but their position wasn't effective in keeping Schumer out of the leadership race at the time.
The vote on leadership posts won't happen until after the 2016 election, and the election for those spots is conducted by secret ballot.