After a victory in the New Hampshire primary and a strong finish in Iowa, Vermont Senator Bernie Sanders appears to be a front-runner at this early stage for the Democratic nomination for president, leading some in the Senate to raise alarms.
Senators supporting Joe Biden, who had a dismal fifth-place finish in New Hampshire, expressed concern about Sanders' ability to appeal to moderate voters and fear the impact his nomination may have on down-ballot races.
Senator Bob Casey said that he's most concerned about electing a nominee who can appeal to voters in Pennsylvania, the state he represents.
"I think there are a number of candidates who can win. I think Joe Biden's best positioned to do that to carry Pennsylvania," Casey told reporters. "Now we're moving into a period in the primaries where you're getting into states that are a lot more diverse, more reflective — not just to the primary electorate but the general election."
The former vice president, who has historically had strong support among black voters, has argued that he will have a stronger performance in states more diverse than mostly white New Hampshire and Iowa. He is particularly hoping for a win in South Carolina, which has a large black population and could therefore be a make-or-break contest for his campaign.
Senator Chris Coons of Delaware, another one of Biden's surrogates, warned that having Sanders at the top of the ticket could hurt Democratic senatorial candidates in more conservative states.
"I do think as someone who has met with and spoken to most of the incumbents who face tough races and the challengers who we need to win, to take back the Senate, they're concerned about who's at the top of the ticket, because frankly, all of the Senate races will be national," Coons said.
Coons also argued that Biden will do better in Nevada and South Carolina.
"Joe is doing what he needs to do. He's on the ground in Nevada, he's on the ground in South Carolina. He's connecting with people, he's listening to people, he enjoys a long and good relationship with folks in these two much more representative states than New Hampshire and Iowa," Coons said.
Senator Michael Bennet, who dropped out of the presidential race on Tuesday after disappointing results in New Hampshire, said a Sanders nomination "could be challenging in parts of the country that we have to win in order to win the presidency and win a majority in the Senate."
However, Bennet said he would support the eventual nominee, a familiar refrain among Senate Democrats. Senator Mark Warner noted to reporters that he had successfully avoided weighing in on the primary for months.
"I'm going to support the nominee, I've not taken a position at this point," Warner said. "There's a lot more chapters to write on this whole process and I don't have the foggiest idea of who is going to come up top."
"I'll support anybody who's the nominee. I'll support you if you're the nominee," Senator Sherrod Brown told a reporter who asked if he would support Sanders should he win the nomination. "It's so early in the process. There's been one kind of screwy caucus, one primary."
Brown did express some admiration for former New York City Mayor Michael Bloomberg, who recently questioned whether Mr. Trump was really a billionaire.
"I loved when somebody asked him, 'does the country want two billionaires running against each other?' And he said, 'who is the other one?'" Brown said about Bloomberg. "So that tells you one how well he knows Trump, and second, how smart he is. And I'll leave it at that."
As for the other two Democratic senators still running for president, Elizabeth Warren and Amy Klobuchar, they say they are gearing up for a long primary process.
"I think it's likely to be a long process. And fortunately, we've built our model for the long haul," Warren told reporters Wednesday.
Klobuchar noted that it was still early in the process.
"It's just the beginning of the race," she said to one reporter, who asked if there are too many centrist candidates in the race. "A primary goes for a while."
When explicitly asked if Joe Biden should drop out, Klobuchar laughed and said: "I'm running my own campaign."
Miles Nuzzi, Alan He and Julia Boccagno contributed to this report