“The first months of the new Senate will be among the most important in American history,” he recently told the Globe. “I may be a little immodest, but I called the governor and said I think I can be a help in reaching a fair solution to some of these issues.”

Frank's decades of experience in the House, coupled with his work on financial regulations as chairman of the House Financial Services Committee, make him particularly well-suited to act as interim senator, his supporters say.

And the upcoming issues facing the government are why, Frank said, he called Patrick last week to let him know he wanted the job. No other potential candidate has made any mention of discussions with Patrick, and Patrick has made no indication which he prefers.

But Rubin's tweet this weekend seemed to indicate that Frank was not a shoo-in for the seat. Though he insisted in a follow-up interview he was simply speaking for himself, he also stood by his initial statement, that Frank may not be the best option, suggesting that Massachusetts "sorely need[s]" "some fresh ideas and energy."

“The theory that we have to send experienced people to Washington to break the gridlock — the experienced people are the ones creating the gridlock,” he said.