Hillary Clinton is in Indiana for a number of events today, while Barack Obama is in West Virginia. With just over a month to go before Pennsylvania voters head to the polls, the Keystone State is already so passe. Recent polls show Clinton leading by a wide margin -- up 16.6 points in the latest RCP Pennsylvania Average -- and Obama has largely moved on to focus on other states.

That's nothing unusual this year. Each time one candidate takes a lead in one state, the other will play down that state's importance and move to the next stop on the calendar. Democrats privately gripe that the extended contest will hurt them in November, and in truth, that's both candidates' fault. Neither has decided to play strongly on the other candidate's turf.

At some point, a battle royale will have to take place. Clinton has already hinted that she may take a pass on North Carolina, which holds its nominating contest on May 6 (and where Obama leads the latest RCP North Carolina Average by 5.4 points), and Oregon, which votes May 20, should be good Obama territory as well. If Clinton plays in either and wins, those victories would go a long way toward her securing the nomination.

Obama, on the other hand, has the opportunity to score on Clinton turf in West Virginia, which votes May 13, or Kentucky, the following Tuesday, May 20. Wins in either of those states could potentially knock Clinton out of the contest.

Indiana remains a toss-up, and each candidate has advantages. Clinton will likely do well in the state's eastern and southern regions, where blue collar whites make up a heavy portion of the electorate. Obama will perform well in Indianapolis, where African Americans are dominant in Democratic circles, as well as the western region of the state, which is in his home media market. So far, Obama has not lost a state that touches Illinois.

It would seem obvious that Indiana is the one remaining battle ground. If Clinton wins, she will wholly own the momentum, and super delegates may begin to break more quickly for her. If Obama takes the prize, he could build a delegate lead large enough to renew calls for Clinton to leave the race.

But we heard the same thing about Pennsylvania. In fact, a Clinton adviser tells CBS's Fernando Suarez, no one has a plan to end the race. "The campaign will go on until all the states and Puerto Rico have voted," the adviser said. Puerto Rico's primary, on June 1, happens two days before the final two scheduled contests, in Montana and South Dakota.