Mitt Romney got a big win, but he's still not the undisputed winner.

Republican presidential candidate Mitt Romney's big win in Tuesday's Illinois primary election gave his campaign a needed boost, and GOP power brokers have since tried to add to his momentum by suggesting Romney is the party's inevitable nominee.

Within a day of Romney's win, former Florida Gov. Jeb Bush announced his endorsement of the Romney candidacy. Bush, no doubt, is hoping that his decision to back Romney will help bring a quick end to what has become a long and nasty battle.

But despite Romney's win in Illinois and his lead in the race for delegates, this fight is far from over. Romney needs 1,144 delegates to win the GOP nomination, and, with roughly 440 delegates, he's not even halfway there.

Obviously, he's way ahead of rivals Rick Santorum, Newt Gingrich and Ron Paul in total delegates. But this contest is not so much about any of Romney's rivals securing 1,144 delegates as it is their collective ability to deny Romney 1,144 votes.

If they succeed, the GOP presidential nominating convention could result in a political free-for-all that could bring a new candidate into the race. It's been decades since either party has had such a brokered convention, but that possibility remains alive in 2012 for the Republicans.

Romney, of course, could use his Illinois win as a starting point for running off a string of big wins that will seal the deal. But if he runs in future primaries as he has in the past, it won't happen.

That would mean many more weeks of internecine warfare among the GOP candidates, and that would be good news for the Democrats and President Obama.

Four years ago, it was the Democrats — Barack Obama and Hillary Clinton — who were at each others' throats. This year, it's Romney and his increasingly embittered rivals.

It's the nature of the political beast, but that reality isn't much comfort to GOP party leaders who'd rather focus on defeating the incumbent than refereeing a fight within the family.