Senate Minority Leader Mitch McConnell's former campaign manager had not actively run the campaign for months before his resignation last week, Republican sources said.

After guiding the Kentucky Republican through a contentious primary, Jesse Benton was essentially replaced by McConnell's former chief of staff on Capitol Hill, Josh Holmes.

Last week, Benton resigned amid questions over his involvement in a payoff scandal associated with Rep. Ron Paul's 2012 presidential campaign.

But two Republican operatives close to the campaign said his work was already done at that point. McConnell had hired Benton to fend off well-funded Tea Party challenger Matt Bevin in the May 20 primary, which McConnell won easily.

After that, the political and day-to-day leadership of the operation shifted to Holmes, who was viewed inside McConnell world as better positioned to captain the re-election campaign in a general election against competitive Democratic challenger Alison Lundergan Grimes, the Kentucky secretary of state.

Benton has close ties to Kentucky Republican Sen. Rand Paul and has been positioning himself for a role running his likely 2016 presidential campaign.

But he's also faced questions for his role in Paul's father's campaign in 2012.

A former Iowa lawmaker who worked on a rival campaign that year pleaded guilty last week to secretly receiving payments totaling $73,000 to switch his support to Ron Paul.

Holmes is also close to Rand Paul. After winning the 2010 Senate primary, Paul made several strategic missteps and McConnell dispatched Holmes to Kentucky to help in the campaign's final weeks.

Rebecca Berg contributed to this report.