Sen. John Fetterman, D-Pa., warned Friday that Democratic Senate nominee Abdul El-Sayed could cost his party a must-hold Michigan Senate seat, escalating a personal feud over El-Sayed’s campaign style, opposition to military aid for Israel and alliance with far-left streamer Hasan Piker."He has put, you know, that seat in play," Fetterman said during an interview with The Washington Post. "And after Bernie Sanders and others created the disaster in Maine, and they pushed garbage person like Platner, and now they’ve pushed an individual like El-Sayed that’s been very proud of his very deeply anti-Israel views and proud to campaign with an avowed communist overall."The Michigan contest is one of roughly a dozen races expected to determine control of the Senate.El-Sayed defeated establishment-backed Rep. Haley Stevens, D-Mich. More than $80 million poured into the primary, the most expensive Democratic Senate nomination contest in history.El-Sayed will face former Republican Rep. Mike Rogers for retiring Democratic Sen. Gary Peters' seat.EL-SAYED PALS AROUND WITH FAR-LEFT STREAMER HASAN PIKER THE DAY BEFORE CRUCIAL MICHIGAN SENATE ELECTIONPiker had made repeated appearances with El-Sayed, including at a Detroit pool party the night before the primary. The streamer has previously said America "deserved 9/11" and praised Mao Zedong as "one of the great leaders of this world."El-Sayed has said he does not share all of Piker’s positions but resisted calls to distance himself.The Republican National Committee seized on El-Sayed’s ties to Piker, accusing Democrats of failing to confront the nominee’s political associations."El-Sayed is a terrorist sympathizer and an America-hating socialist. His refusal to distance himself from Hamas-hugging radicals like Hasan Piker reaffirms his true allegiance is to terrorist groups, not America," RNC National Spokesperson Natalie Baldassarre told Fox News Digital on Sunday.She continued, "Democrats' refusal to disavow this clown shows they either share his poisonous ideology or they're too cowardly to confront it."SEE IT: MICHIGAN DEM PREDICTS FAR-LEFT EL-SAYED WILL WIN SENATE RACE AFTER BACKING HIS PRIMARY RIVALFetterman challenged El-Sayed to maintain that relationship as he moved beyond the Democratic primary electorate."I dare you to continue to campaign with people like Hasan Piker because he now will quickly find out it’s easy to campaign in the echo chamber as a Democrat," Fetterman said.Fetterman's warning broke with Peters, who backed Stevens but who told Fox News Digital that El-Sayed would defeat Rogers because of the candidates' differences on issues affecting Michigan families."And in the end, that’s why he will prevail," Peters said.The dispute turned personal after Washington Post host Kate Andrews played a clip of El-Sayed criticizing Fetterman’s approach to Midwestern politics and temperament.DEMS' LEFTWARD LURCH GETS LEGS AS EL-SAYED'S MICHIGAN SENATE VICTORY SPARKS PARTY DEBATE"Fetterman is probably the biggest issue. Fetterman is the sitting counterargument to the kind of Midwest politics that I think really can work," El-Sayed said. "He’s also just an a——. I try to give him the benefit of the doubt. It’s just he seems miserable, and he seems like he doesn’t like the job."Fetterman answered by pointing to El-Sayed's conduct during the primary."He just has like this weird little man syndrome energy just going around insulting people," Fetterman said. "And, you know, that’s the kind of campaign that he’s run."El-Sayed had sought to reassure Democrats before the primary that he would unite supporters of his rivals against Rogers.CLICK HERE FOR MORE COVERAGE OF MEDIA AND CULTURE"I think everybody understands what the stakes are. So I’m looking forward to welcoming everybody who might have voted differently in the primary," El-Sayed previously told Fox News Digital.That unity effort suffered an early setback Friday when former House Judiciary Committee Democratic chief counsel Julian Epstein told Fox News Digital that he would support Rogers, saying the Democratic Party had moved too far left and "lost its moral center."Fox News Digital reached to Fetterman, El-Sayed and Rogers for comment, but did not immediately receive a response.