WASHINGTON — Campaign watchdog groups blasted Austin lawyer Trey Trainor on Wednesday, warning senators that his ties to the White House and views on campaign finance should raise "significant concerns" should he win a spot on the Federal Election Commission.

Ten groups wrote a letter to senators expressing their concerns, though they stopped short of urging the Senate to reject the nomination.

"Americans expect and deserve an FEC that does not allow special interest to run roughshod over our campaign finance laws, and the Senate must take great care to make sure Trey Trainor is not just another fox to guard the henhouse," said Karen Hobert Flynn, President of Common Cause. "Trainor has exhibited an open contempt for many of the campaign finance laws he would be charged with enforcing at the FEC which is deeply troubling at a time when the agency is mired in dysfunction, unable or unwilling to enforce the laws passed by Congress."

President Donald Trump nominated Trainor earlier this month. The FEC enforces federal campaign finance laws. The pick is subject to Senate approval.

Although he initially backed Sen. Ted Cruz in the 2016 GOP primary, Trainor later provided legal advice to Trump during a delegate fight at the party's convention. During the transition, he worked for James Mattis, now the secretary of defense. He has served as Texas GOP general counsel since June and has a long history in conservative politics in Austin.

The groups critical of his nomination argue that due to his ties to Trump, Trainor would need to recuse himself from any “pending FEC enforcement matters” on Russian meddling in the election, as well as with Trump’s campaign.

The letter also criticizes Trainor's experience in Texas, where he represented Energy Secretary Rick Perry when Perry was governor, served as general counsel to the secretary of state, and had a private practice as a campaign finance lawyer.

"Mr. Trainor is a prominent defender of secret money in elections," the letter asserts.

Trainor has been a vocal supporter of deregulating money in politics, specifically the Supreme Court’s decision in 2010 lifting restrictions on campaign spending by corporations. He also represented Empower Texans, a tea party group, in a legal battle over having to reveal its donors to the Texas Ethics Commission. He later supported the Texas Senate's efforts to defund the commission.

Critics note with alarm that he has advocated for keeping political donations anonymous.

Trainor’s nomination comes as the FEC faces a looming leadership shortage. All five current commissioners have continued to serve even though their terms have expired.

Trump nominated one commissioner, Republican Matthew Peterson, to be a federal judge. A second commissioner, Republican Lee Goodman, plans to retire by year’s end. Even a swift confirmation of Trainor to replace Petersen would not leave the FEC much wiggle room, as at least four commissioners are needed for official action.

Although Trainor's nomination has angered campaign transparency groups, it has elicited strong support from conservatives.

"I've known Trey for close to a decade and know him to be an excellent and thoughtful lawyer,” Goodman told Public Integrity. “Trey Trainor will bring a principled libertarian perspective to the FEC.”