Mark Halperin starts to ring the knockout bell:

Mitt Romney’s Illinois win could be the beginning of the end of the Republican nomination fight. In order to get there, he faces two challenges: He’ll have to convince on-the-sidelines Republicans to endorse his candidacy, contribute to his campaign, and muscle Rick Santorum and Newt Gingrich out of the race. And he’ll also have to persuade the media to reflect the reality that Romney is the only candidate who can win a majority of the delegates needed for the nomination and that he has a good chance of reaching that milestone well before the party meets for its Tampa convention in late summer.

The Romney campaign had made progress on both those fronts before his Illinois win, but the commanding victory is likely to accelerate his cause in the coming days. Once that happens, the normal rules that have prevailed in past nomination fights will kick back in. Santorum and Gingrich can choose to stay in the race, but they will be marginalized and unable to slow Romney down in his accumulation of delegates. They will become ghost candidates, on the ballot and campaigning, but effectively lifeless. Chatter about a contested convention will be greatly diminished.

Or, at least, this is the narrative the political press and Romney campaign will be pushing. For Romney to get the required number of delegates to win the nomination, he would need to win less than half of the remaining delegates, while Santorum would need to win 70-80% of them. That seems highly unlikely.

At some point there simply must be a reckoning that the Republican Party has nominated a candidate who is incredibly unpopular with their ultra-right base. It’s not clear to me that this will prevent Romney from mobilizing the base in the general election, nor is it clear that any significant portion of the Republican base will abstain from voting because Romney is their candidate. While the GOP primary has been shorter and less closely contested than the 2008 Democratic primary, Clinton voters largely and enthusiastically came home to vote for President Obama. Of course the ideological differences between the two were functionally non-existent, while Romney and Santorum have historically greater differences. Again, time will tell.

While there has been plenty of acrimony between Romney, Santorum and Gingrich, this is politics. At whatever point that Santorum and Gingrich end their candidacies, expect them to pull on big, red Team R jerseys and to helping Mitt with trying to win in November. That’s how partisan politics works and it’s unlikely to stop working that way just because parts of the conservative base are cranky about Mitt Romney not being historically radical enough for their tastes.