Retiring Rep. Barney Frank, D-Mass. talks on Capitol Hill in Washington, Thursday, Jan. 3, 2013, prior to the start of the 113th Congress. Joseph Kennedy III is scheduled to be sworn in Thursday, replacing Frank. (AP Photo/Cliff Owen) Former representative Barney Frank (D-Mass.) (Cliff Owen/AP)

Former Massachusetts Democratic congressman Barney Frank has been very vocal about his desire to join the Senate temporarily. And a major part of his pitch appears to be an effort to show that he can be a loyal Democrat. 

Frank wants Gov. Deval Patrick (D) to appoint him to the Senate, if, as widely expected, Sen. John Kerry (D) is confirmed as secretary of state. He's said he won't run in the special election to decide who would serve the rest of Kerry's term, and endorsed Rep. Ed Markey (D) on Wednesday in that contest during an MSNBC interview. Markey is the choice of Kerry and Senate Democrats campaign arm. 

Frank wants to be in the Senate for only the next few months — the congressman said that he and Markey could be a "tag team" of sorts —  to be a part of the critical fiscal decisions Congress will be making during that time, on issues like the nation's debt ceiling. 

But he's something of a wild card, often speaking his mind freely and refusing to pull punches when he disagrees with other pols or ideas. Recent history shows governors have tended to make very safe Senate caretaker appointments, so it's not difficult to envision Patrick going with someone else. 

But Frank's showing that he can fall in line with the party where it needs him, and show restraint where party leaders will want it. In addition to backing Markey, he recently pulled back his criticism of former Nebraska senator Chuck Hagel, President Obama's nominee for defense secretary. 

For those who may be questioning Frank's predictably and raising the possibility of him causing headaches even within his own party, the congressman appears to be making an effort to show that he won't be a problem.