Sooner or later, if the debt ceiling is to be increased, some kind of bill will need to be passed out of the Democratic-led Senate. Unless Senator Harry Reid, the majority leader, is willing to take a procedural gamble, it will need 60 votes to overcome a Republican filibuster.
Mr. Reid has 51 Democrats and two independents who caucus with him. Not all are guaranteed to support him: the moderate Senator Joe Manchin of West Virginia, for instance, has criticized Mr. Reid’s bill as well as Republican approaches.
Still, Democrats have behaved in a far more unified fashion on the debt debate than they do ordinarily. Most likely, Mr. Reid will be looking at somewhere between zero and two Democratic defections and will need somewhere between 7 and 9 Republicans to support him.
The first four Republicans who might support Mr. Reid are easy to determine: Scott Brown of Massachusetts, Susan Collins and Olympia Snowe of Maine, and Lisa Murkowski of Alaska. They were the four Republicans who did not sign a letter spearheaded by Senator Mitch McConnell, the minority leader, expressing opposition to Mr. Reid’s bill. (They also have among the most moderate voting records in the Senate overall.)
But even if Mr. Reid could get these four senators on board, as well as persuade Mr. Manchin to approve some compromise bill, he’d still need three more Republicans. Who are the most likely candidates? I’d list them roughly in this order.
Mark Kirk of Illinois. Mr. Kirk has kept a low profile so far, but has a long track record of moderate and bipartisan votes in the House, where he served for 10 years. He is from a solid blue state and will not be up for re-election until 2016, meaning that he should have little to fear from a primary challenge.
Kay Bailey Hutchison of Texas. Ms. Hutchison is retiring and might be more free to vote her conscience. She’s also been quite vocal about the need to reach a compromise.
Lamar Alexander of Tennessee. Mr. Alexander is on Democrats’ list of “gettable” votes. And although his track record is not extraordinarily moderate overall, he is an old-fashioned deal-maker who sometimes makes exceptions on the most important votes. For instance, he voted to confirm Sonia Sotomayor to the Supreme Court in 2009. Mr. Alexander had expressed his support for the bipartisan “Gang of 6″ plan.
Bob Corker (Tennessee). Mr. Corker has offered some tepid praise for Mr. Reid’s bill. Like his colleague Mr. Alexander, his past voting record is conservative overall but has shown streaks of moderation. One complication is that he’s up for re-election next year, although a credible primary challenge has yet to materialize against him.
John McCain (Arizona). He’s not on Democrats’ target list. And his voting record, once quite moderate, has shifted back to being very conservative since the 2008 elections. But Mr. McCain is among the least predictable votes in in the Senate and has sharply criticized the Tea Party in recent days.
Charles E. Grassley of Iowa. Although Mr. Grassley’s voting record is quite conservative on the whole, he has represented a moderate state in the Senate for more than 30 years and has a reputation as a deal-maker: for example, having been part of the (unsuccessful) efforts to negotiate a bipartisan compromise on health care in 2009. Mr. Grassley, in between tweets about disgusting food at the Iowa State Fair, has told reporters that he won’t support Mr. Reid’s bill as is, but sees hope for a compromise.
Richard G. Lugar of Indiana. Ordinarily, Mr. Lugar is among the most moderate Republican senators. He has bucked his party on many occasions in the past and, at 79 years old, he may be thinking about his legacy. The problem is that he faces an extremely competitive primary next year against Indiana State Treasurer Richard Mourdock, who has the backing of the Tea Party movement.
After that, things get very dicey. The three Republican members of the “Gang of 6″ — Saxby Chambliss of Georgia, Tom Coburn of Oklahoma and Mike Crapo of Idaho — make some Democratic target lists. But Mr. Reid’s bill is not particularly close to the “Gang of 6″ framework, and all three lawmakers are quite conservative by nature.
Of course, it is not necessarily the case that Mr. Reid will pass a bill by picking off Republicans one at a time. The House will need to approve any package too, and that means at least some level of buy-in will be needed from Republican leadership. If Mr. McConnell were to explicitly endorse a compromise effort at some later stage, for instance, Mr. Reid could quickly go from fifty-something votes to 70 or 80.