Former Massachusetts Rep. Barney Frank amped up his push to be appointed interim senator Wednesday night, arguing that his experience made him uniquely qualified for the position.

In an interview on the MSNBC program, “Last Word with Lawrence O’Donnell,” the Democrat said the next three months on Capitol Hill may be “as important a set of three months as we’ve had since the New Deal” and argued he was best person to represent the Bay State during that time.

“That’s why I volunteered,” he said. “And I did have people say, ‘Well, you’re not supposed to volunteer.’ And, frankly, my view is that’s kind of junior high school stuff. The difference between me and a number of other people who want to be the interim senator are I’ve said so publicly and the rest are being coy.”

After Democratic Sen. John Kerry’s expected confirmation as secretary of State, Democratic Gov. Deval Patrick will appoint a senator to fill the vacancy until a special election is held. That interim senator is expected to pledge not to run in the election.

Democratic Rep. Edward J. Markey has already announced his candidacy in the special election, and although he is backed by Kerry and the Democratic Senatorial Campaign Committee, he does not necessarily have a clear field.

Frank said he also backs Markey.

“Ed Markey should be and will be the next senator. Ed and I have worked together in Congress and, before that, in the legislature,” Frank said. “And I would like to think of this as something of a kind of a relay team.”

Frank is not the only person who would like Patrick to appoint him. The Progressive Change Campaign Committee — the liberal group that, among other things, began an effort to draft Elizabeth Warren to run for Senate — launched an effort Wednesday for Patrick to appoint Frank.

And the Boston Globe also endorsed the idea in an editorial Monday. “Giving Barney Frank a platform, even for four months, may give Patrick a little pause. There will surely be some off-key sound bites … but also a lot of sharp thinking and brilliant analysis,” the paper wrote. “Behind the cantankerous personality is an unusually strong legislative mind. Frank is fully deserving of the appointment. “

Patrick is not expected to announce a decision until the vacancy is official.