Former President Trump's dominance in the Iowa caucuses — and his expected triumph in New Hampshire — has the Republican Party buzzing with speculation about potential running mates.

Why it matters: The return of Washington's favorite parlor game is another sign that Trump's nomination — just days after the first votes were cast in the GOP primary — is being treated as inevitable.

The big picture: The stakes are far higher than in 2016.

• Former Vice President Mike Pence is viewed as a traitor in MAGA world for certifying President Biden's election win in the aftermath of Jan. 6 — making unconditional loyalty to Trump a top priority for any potential running mate.
• But when the Republican Party is still fractured — and questions persist about Trump's vulnerabilities in the general election — the pick must also be strategic.

State of play: Trump told Fox News last week that he's already decided on a running mate. His campaign downplayed that claim, but there's little doubt — based on media reports and chatter from top surrogates — that a shortlist has emerged:

1. Rep. Elise Stefanik (R-N.Y.), the chair of the House GOP conference, is "at the top," former Trump chief strategist Steve Bannon told NBC News.

• Stefanik was the first member of Congress to endorse Trump and will campaign with the former president in New Hampshire tomorrow ahead of the state's Jan. 23 primary.
• "She's a killer," Trump reportedly told allies in December, shortly after Stefanik's viral confrontation with university presidents at a hearing on campus anti-Semitism.

2. Sen. J.D. Vance (R-Ohio) is one of Trump's most outspoken defenders in a Senate GOP full of skeptics, sharing the former president's populist views on immigration and "America First" foreign policy.

• "I'd love to see a J.D. Vance," Donald Trump Jr., who prides himself on his ability to channel the MAGA base, told Newsmax as he rattled off his shortlist. "People who are principally in alignment as well as aggressive."

3. Nikki Haley has insisted she doesn't "play for second," but a unity ticket — which Trump was reportedly considering in December — could help attract moderates and swing voters that he'll need for the general election.

• The pick would trigger all-out revolt in MAGA world, however, as Haley's hawkish foreign policy views and establishment ties are anathema to everything expected in a second Trump term.
• "I would not only not vote for that ticket, I would advocate against it as strongly as I could," Tucker Carlson — himself a dark-horse VP candidate — pledged last month.

What to watch: Other names in the mix include Sen. Tim Scott (R-S.C.), Vivek Ramaswamy, South Dakota Gov. Kristi Noem, former HUD Secretary Ben Carson, Rep. Byron Donalds (R-Fla.) and Arizona Senate candidate Kari Lake.