The former top public safety official in Gov. Brian Kemp’s administration on Friday endorsed U.S. Rep. Doug Collins’s campaign for U.S. Senate, siding with the four-term Republican over the governor’s hand-picked choice for the seat.

Mark McDonough, the ex-commissioner of the Department of Public Safety, and 18 county sheriffs backed Collins in the free-for-all November special election against U.S. Sen. Kelly Loeffler, a financial executive Kemp tapped to the seat months ago.

McDonough's endorsement came days after U.S. Rep. Drew Ferguson announced his support for Collins, becoming the first Republican member of Georgia's congressional delegation to take sides in the race. Since then, several congressional candidates and a Washington-based super PAC have also backed his bid.

“Doug Collins supports the law enforcement community and we strongly endorse him as our next U.S. senator,” said McDonough, who heads the “Law Enforcement for Doug Collins” team.

McDonough, appointed to lead the Georgia State Patrol by then-Gov. Nathan Deal in 2011, was forced to retire by Kemp in February. Though McDonough said the governor didn't cite a reason for the change, it came after a cheating scandal cost 30 newly-hired state Troopers their jobs.

A first-time candidate, Loeffler has already spent $10 million of her own cash to boost her chances in the November election, a wild contest that features 21 candidates without any party primaries to filter out nominees. And she’s promised to spend at least $10 million more.

But she's facing new headwinds as she tries to settle questions about stock transactions during the coronavirus pandemic that led her to announce she would no longer invest in stocks in individual companies.

Financial reports released this week show that both Republicans raised roughly the same amount - $1.1 million – over the first three months of the year. But the two were out-raised by the Rev. Raphael Warnock, who collected about $1.5 million since entering the race in late January.

The governor has tried to rally the party's establishment around Loeffler, who quickly nabbed support from Lt. Gov. Geoff Duncan and former U.S. House Speaker Newt Gingrich. She also has the backing of the National Republican Senatorial Committee and several local conservative groups.

But Collins’ camp hopes the recent endorsements of well-known officials and local sheriffs opens the door for others to publicly back him, even if it risks alienating the governor and his allies. The congressman, the son of a state Trooper, said he was particularly touched by the law enforcement backers.

“To say I’m humbled is an understatement,” he said.