Low Republican turnout in today's primaries and caucuses is to be expected. Their race was effectively over before it began. But, given the Republican tendency to rally around a clear winner, McCain's showings among those hardy few Republicans that did vote is remarkably low.
In Texas, McCain garnered only about 52% of the vote. In Ohio, McCain won 60% of the vote. Rhode Island Republicans gave McCain 65% of their vote. Liberal leaning Vermont Republicans gave him 72% of their vote, but aren't typical of the Republican party at large.
McCain is a GOP nominee with plurality support, but not a mandate from the mix of Republican and independent voters who have a say in the decision. I haven't crunched the exit poll numbers, but it isn't clear to me that McCain was even a plurality candidate among Republican voters prior to Romney's departure from the race.
Also, while low turnout for Republicans at this stage of the game is not surprising, a pervasive trend in this primary season has been the far higher turnout for events related to the Democratic party nomination than for the Republican nomination, ever since Iowa, even in many states that have traditionally leaned towards Republican candidates.
Yellow dog Republican are still going to vote for McCain, but will they send money and volunteer their time for his campaign? You know the Republicans are disorganized when the Republican National Committee chairman is sending a mass mailing to me, a treasurer of the Democratic Party of Denver, why I don't send him money anymore. Do they not have voter registration information on the Republican side, as we do in donkey land? No wonder it hasn't been a good election cycle for Republicans in the fundraising department either.