Senator John McCain's convincing victories over Mike Huckabee in Wisconsin and Washington State leave the evangelical former Governor of Arkansas with little more to help him through the remaining Republican primaries than a right wing and a prayer. That right wing, moreover, may now prove less reliably his to command than it was earlier in this long campaign.

In Wisconsin, Republicans who describe themselves as conservative or very conservative divided almost equally between Mr McCain and Mr Huckabee, a sign that the party is beginning to cohere around Mr McCain now that he is all but certain to be nominated at the Republican convention in September. Mr Huckabee appeals to precisely those Republicans that Mr McCain finds hardest to reach, ultra-conservatives and the Religious Right, and he may yet score well in delegate-rich Texas; but he would have to win big majorities in every remaining state contest to come within a mile of giving Mr McCain a run for his money.

Given this arithmetic, some GOP grandees have started to hint that Mr Huckabee would serve the Republican cause best by bowing out now since, whatever he is still in the race for, it cannot realistically be the White House. They argue that Mitt Romney, the other darling of the Republican Right, cited the imperative of unity in “time of war” when he not only withdrew after Super Tuesday, but endorsed the rival whom he had fought so bitterly. The idea is that if Mr Huckabee were to follow suit, Mr McCain would be free to concentrate his firepower on the Democrats, whose own tight and increasingly acrimonious nomination battle could roll on right up to and through their convention in August.

To this extraordinarily unconfident argument - which is not, significantly, subscribed to by Mr McCain himself - Mr Huckabee shows no sign of listening. A Baptist preacher, he has said that he “majors” in miracles, and intends to stay in the race until Mr McCain has secured every last one of the 1,191 delegates he needs to seal the nomination. Mr Huckabee represents, he says, “the heart and soul and base” of the party, conservatives “who feel that their voice still ought to be heard” - and besides, he adds: “What is an election if we don't actually take a vote?”

These are admirably democratic sentiments. They are just what Mr McCain needs to hear. It is vital to keep interest alive. The price of Republican “unity” as this early stage would be to render the party almost invisible from now to August, as all American eyes glued to the Democrats' race between Hillary Clinton and Barack Obama.

The strength that Mr McCain shares with Mr Obama is his appeal to independents who say they are not wedded to either party, a group that currently makes up fully a third of the electorate. But he can ill afford to alienate conservative Republicans. It is not in the man's nature to pander to them, so he needs time to reconcile them to his candidacy, if only by convincing them that he can win. He cannot do so unless they stay engaged. Primary turnouts so far suggest that Democrats have a stronger will to win than Republicans this year. There remains a risk that, come November, Huckabeeites could put ideology before victory and stay home. Mr Huckabee and Mr McCain are as different as chalk and cheese. For that very reason, the Republicans need both men to stay in the political ring.