Barack Obama’s campaign issued an e-mail on Tuesday night that appeared to relegate Hillary Clinton’s lead in Indiana to efforts by Rush Limbaugh to wreak havoc in the Democratic presidential primary contest.

In an e-mail entitled “The Limbaugh Effect in Indiana = 7 percent,” Obama campaign spokesman Bill Burton wrote: “According to the latest exit polling data, 17 percent of voters in the Indiana primary today said they would vote for John McCain in a Clinton/McCain match-up. Forty-one percent 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 percent of the primary electorate the number that may be attributed to a Limbaugh Effect.”

Limbaugh has said his scheme to tilt the Democratic primary exceeded his expectations.