Former Rep. Barney Frank (D-Mass.) endorsed Rep. Edward MarkeyEdward (Ed) John MarkeyOvernight Regulation: FTC launches probe into Equifax | Dems propose tougher data security rules | NYC aims to slash greenhouse gas emissions | EPA to reconsider Obama coal ash rule Overnight Cybersecurity: Kaspersky to testify before House | US sanctions Iranians over cyberattacks | Equifax reveals flaw that led to hack Dems propose data security bill after Equifax hack MORE (D-Mass.) in the special election to replace Sen. John KerryJohn Forbes KerryBringing the American election experience to Democratic Republic of the Congo Some Dems sizzle, others see their stock fall on road to 2020 The Hill's 12:30 Report MORE (D-Mass.) if Kerry is confirmed as secretary of State, as is expected.

"Frankly, Ed and I have worked together in Congress, before that in the legislature, and I would like to think of this as something of a kind of a relay team," he said on MSNBC's "The Last Word with Lawrence O'Donnell."

Frank has expressed interest in serving as interim senator after Kerry moves to the Cabinet and before the special election. The interim senator will be chosen by Gov. Deval Patrick (D-Mass.).

Frank, who retired at the end of the last Congress, also told host O'Donnell he "endorses" O'Donnell's position that "Markey should be and will be the next senator" from Massachusetts.

Markey is thus far the only candidate to officially announce his interest in running for the seat, though Massachusetts Democratic Reps. Michael Capuano and Stephen Lynch have also expressed interest. However, shortly after Markey announced his intentions to run, a number of big-name Massachusetts Democrats, including Kerry himself, and the Democratic Party's Senate campaign arm, endorsed him.

In Frank, he now has another outspoken Massachusetts Democrat in his corner. But the idea that Frank and Markey will create a "relay team," as Frank put it, is far from certain. Patrick has not yet indicated whom he favors for the appointment, and Markey is unlikely to have a clear path to the nomination, despite his prominent endorsements.

Frank explained that he wants to go back to Washington immediately to work toward avoiding a series of budget cuts and to raise the debt ceiling. Those legislative deals are likely to include negotiations over entitlement reform. He's argued that his experience over three decades in the House working on financial issues makes him uniquely well-suited for the appointment.

And he emphasized during his Wednesday-night interview that he has no plans to run for the seat, sounding deferential to Patrick's indication that he'd rather appoint a caretaker to the position than someone who would seek the seat in the special election.

"I think this two-step process works well," Frank said, adding that he initially never wanted the appointment.

"On Dec. 28, I didn't really want that job," he said.