WASHINGTON — After Sen. Dave McCormick announced his run against longtime Democratic Sen. Bob Casey in September of 2023, Sen. John Fetterman described the Republican former hedge fund CEO as a “rich dude” who likely will “try to buy a seat in the Senate.”

Now that the heated and costly campaign is over, with McCormick recently swearing in after narrowly defeating Casey, Fetterman and his new Republican colleague find themselves early — and thus far friendly — partners in the new Congress.

The pair and their wives, Gisele Fetterman and Dina Powell McCormick, broke bread together recently, which the social-media savvy Fetterman captured in a thumbs-up selfie posted on X, and which McCormick shared from his new Senate account.

McCormick said they talked “about where we can work together to best serve (Pennsylvania) — from stopping the spread of fentanyl to fighting antisemitism and supporting Israel, and providing the best constituent services for the people of our commonwealth.”

“Two dudes (plus) two better halves (plus) bipartisanship (plus) 67 counties (equals) a stronger Pennsylvania,” said Fetterman, who on Thursday became the first Democratic senator to accept an invitation to meet President-elect Donald Trump at his Mar-a-Lago club in Florida.

The bipartisan vibe was also reflected on the Senate floor Thursday, when Fetterman and McCormick voted together in favor of advancing a Republican-led immigration enforcement and crime-related bill — marking the first of likely many occasions they will join forces on a host of issues impacting Pennsylvanians and Americans at large.

“For better or for worse, they are thrown into a bit of a shotgun marriage,” Larry Ceisler, a Pennsylvania public affairs executive, told the Post-Gazette Friday. “If one cares about their public service, and one cares about their constituents and the commonwealth, wherever you can work together, you'll work together.”

Ceisler, a Democrat, said bipartisanship isn't rare for Pennsylvania's U.S. Senate delegation. He noted that even though Casey and former Sen. Pat Toomey, a Republican, were “ideologically opposed on nine-tenths of issues, they found a way to work together” for more than a decade.

Ceisler said former Sen. Rick Santorum, a conservative Republican, also worked well with the more moderate Sen. Arlen Specter, Pennsylvania's longest-serving senator, who was a Republican for most of his tenure including a few years opposite Casey, before switching to the Democratic Party in 2009.

“It can be such a powerful combination when you have two senators of different parties rowing in the same direction,” he added. “What we're seeing so far, I think, is very positive. It's very apparent that both (Fetterman and McCormick) are beyond the campaign and they're looking to governing, and looking to their futures.”

While the Keystone State has been accustomed to a split delegation in recent years with Casey and Toomey, its current dynamic in the Senate is increasingly unique nationwide.

After the Republican takeover of the Senate driven in large part by strong turnout for Trump, Pennsylvania is one of only three states — along with Maine and Wisconsin — with a split U.S. Senate delegation. That's the fewest split Senate contingents since the public started directly casting ballots for senators more than a century ago, The Washington Post reported.

Of the 25 congressional terms over the last 50 years, there have been 12 (including the new Congress) in which opposing parties represented Pennsylvania in the Senate.

The commonwealth is also unique in that its now-senior senator, Fetterman, has only been in office for two years — marking an unusually short gap between a senior and freshman senator from the same state.

Republicans say McCormick, the highest ranking Republican in Pennsylvania, is poised to become a strong state and national leader on issues such as energy, immigration and the economy.

McCormick recently told the Post-Gazette that he and Fetterman agree on their strong support for Israel and combating antisemitism. He added that his Democratic colleague is “focused on jobs for working families, manufacturing — that's what I'm focused on.”

“This is about solving problems for Pennsylvania, so if I can work with Fetterman on those issues, he's going to find a great, supportive colleague in me,” he added.

Fetterman told reporters last week at the Pennsylvania Farm Show in Harrisburg that he and McCormick had already met for dinner in Pittsburgh, had a “great discussion” and will work together as they both “want a better Pennsylvania.”

“It's not just a fellow senator and a colleague, it's a person you get to know to at least some extent,” Christopher Nicholas, a Harrisburg-based Republican consultant, told the Post-Gazette. “Just because they're different parties doesn't mean they're going to be opponents — or best buddies.”

Experts said the pair are likely to work together on immigration policy, foreign policy, urging the release of Oakmont teacher Marc Fogel from Russia, and seeking to keep steelworker jobs in Western Pennsylvania amid tumult over U.S. Steel's potential acquisition by Japan's largest steelmaker, Nippon.

Among other issues, they may have disagreements over spending — with lawmakers needing to come to a funding agreement by mid-March to dodge a government shutdown. And Republican House members and senators — already heavily influenced by Trump as a candidate and president-elect — are sure to feel even more pressure from the White House once Trump is in power.

Nicholas, who worked on several of Specter's campaigns, said a big question remaining is “what's going to happen six months from now — some calamity or new wrinkle on the immigration issue, where Trump wants to do his mass deportation and how that plays out.”

“I think they'll quickly figure out, you may be at loggerheads on issues, but once you get back to the state, it's 'Hey, we're all Pennsylvanians. What's best for Altoona or Butler?'” he said.

He added that several senators don't get along even if they are from the same state and party.

Nicholas said while the pair may not agree on all of Trump's cabinet and administration nominees — though Fetterman has endorsed some already, unlike most Democrats — it's critical that they work together on federal judiciary appointments. That's an area where Casey and Toomey often touted bipartisanship.

“They have to work some sort of relationship on that, because people are always retiring or dying unfortunately, so you've got seats open in Pennsylvania and in the judicial district we're in,” he said. “You want to have those slots filled (as soon as possible), because otherwise you get a backup and things slow to a crawl … you can't investigate the bad guys, arrest them, and then not get to their day in court. That issue never goes away. It's like delivering the mail.”

Meanwhile, the outspoken Fetterman is “going out of his way to demonstrate he wants a dialogue with the incoming Trump administration,” Nicholas said.

“Unlike most in his party, he's not automatically defaulting to opposing everything,” he said.

In September during the heated campaign, Fetterman blasted a Trump rally in Erie as “not a campaign speech. It's a disheveled dude in a sloppy disjointed rant about random shit.”

He noted that even his pick for vice president, Sen. JD Vance of Ohio, publicly said Trump “didn't deliver” on his promises during his first administration.

But now, Fetterman — who vigorously pushed for Casey's, President Joe Biden's and Vice President Kamala Harris' campaigns — faces the prospect of a Republican trifecta: control of the Senate, House and White House.

“President Trump invited me to meet, and I accepted,” he said Thursday. “I'm the senator for all Pennsylvanians — not just Democrats in Pennsylvania.”

He added that “no one is my gatekeeper. I will meet with and have a conversation with anyone if it helps me deliver for Pennsylvania and the nation.”

Ceisler sees the upcoming meeting between the senator and Trump as a positive.

“As polarized as our country seems to be, I think there is a desire for people to be able to cross the aisle,” he said. “There is some desire for some type of civility when possible, and I think Fetterman wanting to have a first meeting and possibly a relationship with Donald Trump is positive. It's not like we don't know where he stands on Donald Trump.”

Ceisler said lawmakers can “live in some political fantasy world or you can deal with the reality of the moment.”

He also suggested the senator appears to have shrugged off concerns about any political damage after embracing Trump nominees, expressing strong support for Israel and being open to working across the aisle.

“He understands his politics and understands the process as well as anybody,” he said. “So whatever he's doing, if the perception is it's going to hurt him, he obviously doesn't think it's going hurt him enough.”