WASHINGTON (AP) - Mitt Romney says he's "almost there" in his six-year pursuit of the Republican presidential nomination, having defeated Rick Santorum in the Illinois GOP primary.

The GOP front-runner is urging Republicans in a campaign email sent after Tuesday's victory to fall in line behind his bid.

Romney and his allies spent hundreds of thousands of dollars more than Santorum and his backers in Illinois, and it showed in the results: Romney was beating Santorum by 47 percent to 35 percent.

Romney was the clear favorite among Illinois Republicans who were most concerned about picking someone who is capable of taking on President Barack Obama.

In an appeal to the centrist independents who will decide the general election, Romney pledged to work with Democrats or, in his words, "die trying."