Since the Illinois and Louisiana contests, the spacing of primary contests has spread out, the excitement given to them has waned, and the chances that the direction of the race has shifted has decreased even more.
Also since that date, Mitt Romney has picked up three key important endorsements: President George H.W. Bush, Florida Senator Marco Rubio and Wisconsin Congressman Paul Ryan. The last one, it would seem, would be especially interesting going into the Wisconsin primary.
Wisconsin is an interesting state in this race, because it is next to Minnesota, which Rick Santorum won overwhelmingly in the February caucus, but it is also next to Illinois and Michigan, which Romney won. There was also some thought that Republican voters, ready to wrap up this long race, will finally accede to the inevitable and give Romney the nomination.
Romney did win, by a margin of 44-37%, with Ron Paul and Newt Gingrich picking up small shares of the vote. Romney's win was better than his margin in Ohio or Michigan, but less than in Illinois. Although his margin was small in terms of votes, it was high in terms of delegates, and one more chance for Santorum to pull out an upset has evaporated.
Mitt Romney has won another contest, and his path towards the nomination just became even more likely. It is still somewhat surprising how small the marginal utility for Romney's efforts has been. After the media has hailed him as the "inevitable" candidate, after the top leadership of the Republican Party has endorsed him, and after spending another few million dollars on advertising in Wisconsin, his share of the vote in Wisconsin was still only 44%. Despite his advantages, there seems to be a fairly low ceiling to Romney's popular support.