If Clinton wins, expect to hear more from the Obama camp about Rush Limbaugh’s “Operation Chaos.” Obama spokesman Bill Burton has only sent reporters two notes tonight–and both referenced El Rushbo. Here’s the latest:

According to the latest exit polling data, 17% of voters in the Indiana primary today said they would vote for John McCain in a Clinton/McCain matchup. 41% of that number is constituted by people who voted Clinton in the primary but also indicated they will vote for McCain in the general election. That comes out to just under 7% of the primary electorate–the number that may be attributed to a “Limbaugh Effect.”

The point, of course, is to convince reporters–like the New Republic’s Jonathan Chait, who confirms Burton’s math–to pursue this line of reasoning. If Clinton ekes out an Indiana win, Burton and Co. want the wrap-up stories to suggest that Dittoheads may have (more than) accounted for her margin of victory, thereby delegitimizing it with the only audience that still matters: superdelegates.

Still, Team Obama might not be forced to rely on such spin. With 85 percent of precincts reporting, there are still no results from Lake. The second largest county in the state and the most overwhelmingly African-American, it’s home to Gary, the industrial southern satellite of Chicago. If patterns from the rest of Hoosier Country hold, Obama is likely to rack up a sizable, double-digit margin there and slash into–or even erase–Clinton’s four-point lead. Also worth watching: Monroe County, home of Bloomington and Indiana University, where Obama is up 66-34–with only 43 percent of the vote in.

Perhaps that’s why, as the Clinton campaign sent reporters a memo calling her “victory” in Indiana “incredible,” Clinton herself took the stage in Indianapolis later and less surely than expected–and, looking somber, and promised to work to pull the party together ““no matter what happens.”

Developing…

UPDATE, 12:01 a.m.: The Washington Post’s Alec MacGillis talks to the mayor of Gary:

“Let me tell you, when all the votes are counted, when Gary comes in, I think you’re looking at something for the [world] to see,” [Rudy] Clay, an Obama supporter, said in a telephone interview from Obama’s Gary headquarters. “I don’t know what the numbers are yet, but Gary has absolutely produced in large numbers for Obama here.”

With 28 percent of Lake County precincts reporting, Obama leads Clinton 75-25. Clinton will probably close that gap as the whiter, rural returns come in, but there’s a chance that Obama could erase her 40,000-vote lead statewide, depending on turnout.

Not a good sign: according to the Politico’s Ben Smith, “Tim Russert… just said that Hillary Clinton canceled her scheduled appearances on the morning shows tomorrow. It’s a sign of weakness she can ill afford at a moment when questions about whether she can continue are mounting.”

Still developing…