BATON ROUGE - Republican U.S. Sen. David Vitter is trying to rally last-minute support from conservative voters in advance of Louisiana's Saturday runoff election for governor. The race remarkably shows Democratic state Rep. John Bel Edwards in the lead in a state that usually votes Republican.

The competition has become a slugfest of attack ads and one of the most expensive governor's races in Louisiana history. At least $30 million has been spent by candidates and outside groups.

When Vitter launched his campaign in January 2014, he immediately became the front-runner and pulled in tremendous sums of campaign cash. More recently, the race shifted to a referendum on Vitter, particularly his 2007 prostitution scandal, his campaign tactics and his inability to unify GOP support.

During the runoff, Vitter has lagged in fundraising and polls.