Party leaders heard private concerns about a pro-Lamb super PAC after the group slammed Fetterman as a self-proclaimed Democratic socialist, a claim that led to the ad being pulled from one TV station. Several attendees at the caucus meeting said that Gary Peters, the Democratic Senatorial Campaign Committee Chair, said they were addressing the issue after Sen. Elizabeth Warren raised the ad during the meeting.

I saw the ad that is running in Pennsylvania. It is wrong and disgusting. In an interview on Wednesday, Warren said that if Lamb wants to stand up as a Democrat, then he needs to disassociate himself from that ad.

Rep. Conor Lamb speaks at a microphone outdoors, surrounded by people clapping.

Rep. Conor Lamb (D-Pa.) announces his candidacy for the Senate at the International Brotherhood of Electrical Workers on Aug. 6, 2021, in Pittsburgh, Pa. | Jeff Swensen/Getty Images

Most of the Democrats in the caucus are neutral in the Pennsylvania primary, but they are warm for Fetterman and don't think he will be a bad candidate in the general election. Fetterman came in third in the last open primary, when party bosses endorsed and spent big for McGinty. Jon Tester recalled this week that he didn't pay much attention to the Fetterman campaign.

Fetterman is leading in public and internal Democratic polls by wide margins according to people who have seen them. Fetterman is a kind of populist that I think would do well in Pennsylvania, according to Sen. Stabenow.

Republicans argue that Fetterman is too liberal to win the general election against the winner of a GOP field that includes business executive David McCormick and TV surgeon Mehmet Oz. Peters said he would be comfortable with Fetterman as the nominee.

We won't put our thumb on the scale if I have candidates that can win the general election. Peters said in an interview that the candidates in Pennsylvania can win the election. In Pennsylvania, we have that with the top two candidates.

Fetterman described his campaign relationship with the DSCC as good and said he has spoken with Peters and Warren. He heaped praise onto both of them, calling Warren just a luminary in the Democratic Party and saying he admires Peters for how he makes it work in a state like that.

Senate candidate Pennsylvania Lt. Gov. John Fetterman speaks during a meeting of the Pennsylvania Democratic Party State Committee.

Senate candidate Pennsylvania Lt. Gov. John Fetterman speaks during a meeting of the Pennsylvania Democratic Party State Committee in Harrisburg, Pa., Saturday, Jan. 29, 2022. | Matt Rourke/AP Photo

Fetterman didn't want to talk about how the DSCC handled his campaign.

The hulking, 6-foot-8 Fetterman dresses casually as he fights for marijuana legalization, a $15 minimum wage and other rights. Fetterman met the president in shorts and a hoodie when Joe Biden showed up in his state to survey a bridge collapse.

Fetterman was described as an unusual candidate by Senate Majority Whip Dick Durbin. This is not a typical Democratic candidate.

The decision by the Democrats to forgo endorsing the more moderate Lamb, who holds a tough seat for Democrats in Western Pennsylvania, is an evolution for a party that has spent years playing kingmaker among its Senate candidates. The campaign of Lamb didn't comment on the story.

With the Senate majority on a knife edge, Democrats are trusting primary voters to give them the best candidates rather than weighing in from D.C.

I don't know if we did well in 2020 by getting involved early, said Sen. Chris Murphy (D-Conn.).

Democrats are not likely to intervene in the primary because of Fetterman. McGinty was endorsed by the DSCC a month before the 2016 primary.

There is still concern that the increasingly bitter contest between Fetterman, Lamb and Kenyatta could damage the nominee. Two people familiar with the discussions say that top DSCC aides have expressed displeasure with the prospect of attack ads in the primary.

Republicans will be happy if Fetterman wins the Democratic nomination. Fetterman will face scrutiny in a general election about pulling a shotgun on a black jogger when he was mayor of Braddock, Pa. The lieutenant governor said that he didn't know the man's race or gender at the time, but he thought the jogger might have been shot.

In politics, you should be careful what you wish for. In a general election, the wing of the Democratic Party that supports the idea of socialism is not likely to prevail, according to Sen. Pat Toomey.

Warren wants advice from Republicans on who should be the Democratic nominee.

It brings a smile to my face when I hear Republicans underestimate a candidate. I've been in that seat before.

Some in the caucus would prefer Lamb even if they weren't endorsing him. He liked Lamb more as a candidate than he did as a person. Joe Manchin, who is frequently targeted by Fetterman for standing in the way of filibuster reform and Biden's agenda, said that Lamb would be an outstanding U.S. senator.

Manchin said that he wanted to get rid of the filibuster. I think he fits the bill.

If Democrats lose control of either chamber of Congress this fall, Fetterman might not be able to scrap the filibuster, even if he wins. Fetterman said his message to Senate Democrats as well as the party's voters is that he is their loyal partner.

He said that they were behind the Biden agenda and the Democratic agenda.