Alaska Lt. Gov. Mead Treadwell (R) has parted ways with his Senate campaign manager and top consultant following months of campaign struggles.

Treadwell, once the front-runner for the GOP nomination to face Sen. Mark Begich (D), has posted weak fundraising totals quarter after quarter and has been eclipsed in the GOP race by former Alaska Department of Natural Resources Director Dan SullivanDaniel Scott SullivanSenators demand cyber deterrence strategy from Trump Overnight Energy: Trump to consider elephant trophy imports 'case-by-case' | Zinke makes 'acting' directors official | Senator says Arctic refuge drilling auction could start next year Overnight Regulation: National security review delays bid for Qualcomm | Trump to consider elephant trophy imports 'case by case' | Arkansas Medicaid work rules approved | More companies sue to save net neutrality MORE (R).

"I have had to make one of the toughest decision to this point in our campaign, I parted ways with Adam Jones, Campaign Manager. Rick Gorka, part of the communications team is also leaving," Treadwell said in a statement.

Peter Christensen, Treadwell's national finance chairman and a close friend, is going to take over the campaign on a temporary basis.

Treadwell's move is the latest sign that Sullivan is pulling away in the primary. He has the backing of the conservative Club for Growth as well as many establishment Republicans — the former Bush administration appointee is close with Sen. Rob Portman (R-Ohio) and has hauled in big fundraising sums since he entered the race last fall.

The race in the GOP-heavy state is a top GOP priority.