Mr. Romney, who has 563 delegates, according to an Associated Press count, is almost halfway to the clinching threshold. But the voting calendar is now entering a slower phase that will persist for the next five weeks, until five Northeastern states vote on April 24, with 209 delegates at stake.
The soonest that Mr. Romney could officially clinch the nomination is May 22, when Arkansas and Kentucky vote. That situation would require Mr. Romney to win at least 95 percent of the delegates in Arkansas, Kentucky, Louisiana, Wisconsin, Maryland, Connecticut, Delaware, New York, Pennsylvania, Rhode Island, Indiana, North Carolina, West Virginia, Oregon and the District of Columbia, and to receive endorsements by virtually all of the Republican Party’s 77 undecided superdelegates by that time.
Some of those states, of course, are not so strong for Mr. Romney. And even if he won 70 percent of the delegates in those states, as well as in Texas, which votes on May 29, he would still need to wait until June 5 — when California and New Jersey vote — to clinch the nomination.
(...) The more telling number, therefore, may be this one: Mr. Romney has so far won 56 percent of the delegates, according to the Associated Press count. That is, obviously, more than half — in fact, Mr. Romney’s share of the delegates as calculated on this basis has steadily been inching upward over the course of the last month.
It’s also enough to permit him some slack. Mr. Romney would need to win only 46 percent of the remaining delegates to get to 1,144.
There is no reason to think that the remaining states will be much better or worse for Mr. Romney than the ones that have already voted. He should do well in places like California and New York, but more poorly in states like North Carolina and Texas.
If the remaining states play out according to their demographics, as prior ones have, Mr. Romney should continue to win slightly more than half of the delegates on average. If he wins slightly less than half, he should still have no real problems.