Does McCain Have a Ceiling?

Ron Brownstein, in the latest National Journal:

Just as in 2000, McCain won decisively among moderate and independent voters in New Hampshire. But the final results in the New Hampshire exit poll conducted by Edison/Mitofsky showed that very conservative voters preferred Romney over McCain by more than 2-to-1 ... those results echoed McCain's performance in 2000, when he ran just even with Bush among New Hampshire Republicans and conservatives. McCain then failed to win the 2000 nomination because he ultimately could not attract enough core Republicans in other states. In states with Republican electorates that were more conservative than New Hampshire's -- such as South Carolina, California, Florida, Georgia, and Missouri -- Bush routinely beat McCain among both Republicans and conservatives by at least 2-to-1.

Once again, McCain's most urgent challenge is to expand his appeal among those core Republican constituencies, because few other states are tailored as precisely to his strengths as is New Hampshire. Conservatives represented just 55 percent of New Hampshire Republican voters on Tuesday, according to exit polls. That's lower than in almost any state outside the Northeast.

Likewise, voters who identified themselves as independents (as opposed to those legally registered as independents) cast nearly four in 10 of the Republican ballots in New Hampshire, according to the exit poll. That's a higher percentage than independents contributed in 2000, the last contested GOP presidential race, in almost any other key state -- from South Carolina and Florida to New York and California.

As Brownstein goes on to note, of course, the great advantage that McCain '08 enjoys over McCain in 2000 is the fact that everybody else in the race seems to have a ceiling too. So even if self-described conservatives never start breaking McCain's way, the weakness of his opponents will probably prevent any of them from playing the George W. Bush role from 2000 and sweeping him aside. But at the very least, if McCain keeps stalling out around 35 percent of the vote, he's going to start losing some primaries, and even when they lose his rivals can keep racking up substantial numbers of delegates in the states that aren't winner-take-all. Which begins to makes a brokered convention scenario - which is bandied about every election cycle and never materializes - seem shockingly plausible.