Mehmet Oz has a recurring nickname for his Democratic Senate opponent: Bernie Sanders.

As the general election campaign enters its second full month, Oz, the Republican nominee, along with members of his party, have increasingly tried to connect Lt. Gov. John Fetterman to Vermont Sen. Sanders in fund-raising emails, press releases, and digital ads.

“John Fetterman will befriend Bernie Sanders in the Senate,” Oz tweeted last week. “He will follow Bernie’s lead and be his sidekick. PA and America cannot afford to have another ‘Bernie’ in the Senate.”

Republicans have been quick to draw a comparison between Fetterman and President Joe Biden, whose approval ratings are at an all-time low, but they’re also trying to tie Fetterman to Sanders.

A release from the GOP’s Senate campaign arm read, “Bernie Bro John Fetterman Says He Wants to Turn Pennsylvania into Bernie’s Socialist Hellscape.” It was accompanied by a video montage of clips of Fetterman praising Sanders.

Fetterman and Sanders have swapped endorsements and shared rally stages, as well as some policy views. They’ve run similarly styled grassroots progressive campaigns. That all sets up an easy comparison for Oz to make. Fetterman faced somewhat similar criticism in the primary and coasted to the nomination.

In 2016, following his endorsement of Sanders for president, Fetterman said at a presidential debate watch party in Pittsburgh: “What Bernie wants to do for the U.S., I want to do here in Pennsylvania.” That year both were running as outsiders against the establishment.

Six years later, Fetterman’s campaign has pushed back on the “just another Bernie” characterizations in the midst of a general election in which the lieutenant governor will need to appeal to moderate and independent voters. His campaign points out policy differences and the lack of interaction between the two in recent years, but it’s a tricky balancing act, given how closely Fetterman had aligned himself with Sanders and the progressive movement in the earlier part of his political career.

In an interview with NBC days before the primary, asked if he was a progressive, Fetterman said: “No, I’m just a Democrat.”

“John is not like Bernie, or Biden, or any other politician in Washington for that matter,” campaign spokesperson Joe Calvello said. “He’s John Fetterman, and there is no one else like him. The people of Pennsylvania understand that, and if Dr. Oz was actually from Pennsylvania, he would, too.”

When Fetterman endorsed Sanders — and when he didn’t

Fetterman endorsed Sanders for president in 2016 and stumped for him in rallies and promotional videos. Sanders didn’t return the favor during Fetterman’s 2016 Senate bid, but he did back Fetterman in his 2018 race for lieutenant governor. When Sanders ran for president in 2020, Fetterman opted not to endorse in the race and spoke out against candidates, including Sanders, who were calling for a total ban on fracking.

In his 2016 endorsement of Sanders, Fetterman said he and the independent senator “agree on a lot of” issues.

“Whether it’s immigration, whether it’s marijuana legalization, whether it’s universal pre-K or affordability for college education, we stand together as the most progressive candidates in our respective races, and it’s my pleasure and privilege to stand with Bernie and to have Bernie’s back.”

» READ MORE: Oz blamed his fund-raising gap on the abortion decision. He was trailing well before that.

Fetterman and Sanders align with many in the Democratic Party on issues like supporting a $15 minimum wage, getting rid of the filibuster, marriage equality, and immigrant and LGBTQ rights.

But the Fetterman campaign is keeping its distance and points to other policy differences. Fetterman has said he does not support a ban on fracking. He’s said that if Medicare for All had enough support, he’d vote for it but that he’d also support less expansive health-care reforms. Fetterman has said he agrees with certain parts of the climate package known as the Green New Deal.

The campaign has had 10 joint fund-raisers with current senators, none of them Sanders. Sen. Elizabeth Warren is planning a fund-raiser for Fetterman later this month.

Why Republicans are tying Fetterman to Sanders

Drawing parallels between Fetterman and Sanders, Republicans hope, will paint Fetterman as “radical” and scare off independents and moderate Republicans or Democrats to whom he might appeal.

The Sanders comparisons also come in a moment when Republicans are wondering whether President Biden’s anemic approval ratings will have the expected drag on Democrats in midterm races. A Siena/New York Times poll last week showed Biden’s approval ratings around 39% but a dead heat for which party voters wanted in control of Congress.

There’s an assumption, GOP strategist Vince Galko said, that the GOP base, angry about inflation and with Biden, will turn out. But the Sanders comparisons target soft Democrats and independents.

“You’ve gotta start playing on the offense,” Galko said. “The way you do it is you make the case this isn’t ... Bob Casey from 2006, a traditional Pennsylvania Democrat. This is a pretty woke activist running for Senate. And I think the two leading examples of that are Bernie Sanders and [U.S. Rep. Alexandria Ocasio-Cortez]. So you point to them.”

» READ MORE: Fetterman and Oz spar through sarcastic tweets, a ‘missing’ poster, and an airplane banner

Galko said Oz is also wise to challenge the shorts-wearing, everyman image Fetterman presents, because it’s already shown to have some appeal in more rural parts of the state.

“He’s portraying that image that the Scranton, Wilkes-Barre, or Altoona-Johnstown market wants to see. Yeah, he’s a Democrat, but he’s still a Blue Dog Democrat, which is hysterical, when his record is anything but,” Galko said.

In an Oz fund-raising email listing the five things to know about Fetterman, his support for Sanders’ presidential bid was No. 1.

“Don’t get it twisted — this ‘hipster Democrat’ would absolutely RUIN Pennsylvania,” the email said. “If you think Joe Biden is bad … just wait. John Fetterman is as Radical as they come.”

Will comparisons to Sanders hurt Fetterman?

But it’s unclear how effective invoking Sanders will be. In the primary, Fetterman’s closest rival, U.S. Rep. Conor Lamb, often accused him of being too far to the left to win in Pennsylvania. A super PAC backing Lamb ran ads calling Fetterman a “self-described Democratic Socialist.” The ad backfired when fact-checkers found Fetterman had never referred to himself that way and one news station pulled it off the air.

And some see Oz’s biggest vulnerability — being a multimillionaire who recently moved to Pennsylvania from New Jersey — as a far more damning description to overcome.

Bill Neidhardt, a Democratic consultant and former Sanders staffer, said he didn’t think the attack would be very effective because Sanders remains popular.

“[Sen. Sanders] is regularly one of the most popular politicians in the country,” Neidhardt said. “It’s also pretty well-known that John Fetterman didn’t back Bernie in 2020. Everyone in the Bernie camp remembers that, there was frustration there. That’s just a fact.”

Biden faced similar charges in 2020 that he was a socialist in Democratic clothing, doing the bidding of Sanders and Ocasio-Cortez.

Howard Merrick, who chairs the GOP in Schuylkill County, voted for Oz in the primary and thinks the Sanders comparison could be effective, but no more than connecting Fetterman to Biden.

“It’s all about Biden and the economy,” Merrick said. “That’s the big thing. If he stays on that, he’s gonna do much better. Focus on the thing that bothers most people. Stay on Biden. Skip Bernie.”

Bill Bretz, who chairs the GOP in Westmoreland County, said it’s important for Oz to define his opponent.

“John Fetterman likes to posture himself as some working-class everyman that’s out for small-town America, but the folks who are buying that are just victims of clever and slick marketing,” he said. “John Fetterman is a child of wealth and he has an Ivy League education and ... he may dress like he buys his clothes at Goodwill, but he is every bit as liberal as anybody else.”

While Oz has slammed Sanders in recent weeks, he’s previously said nice things about him — and once played basketball with him on The Dr. Oz Show. In an October 2019 episode of The View, Oz said Sanders, who recently had suffered a heart attack, should continue on with his campaign.

“Bernie Sanders, I really fell in love with,” Oz said then.

”If you’ve had a correctly fixed heart ... the chance of another problem this year is less than 5%, so I say go for it, Bernie,” Oz said then. “You’re in good shape, your protoplasm is strong. Give your passion to America.”

Oz’s campaign said the comments were in reference to Sanders’ health, not an endorsement of his politics.