Former presidential candidate Evan McMullin was one of several Utah Republicans who were eyeing a congressional run in 2018 after the surprise retirement announcement of Rep. Jason Chaffetz.

McMullin confirmed in a Thursday morning email to the Washington Examiner that he had been weighing a challenge to either Sen. Orrin Hatch or Chaffetz in the 2018 Republican primary, and indicated that the congressman's decision to retire could make a run for the 3rd district appealing.

"I've been considering challenging Hatch or Chaffetz, or not running at all in 2018. Obviously, this development today is significant, but there are other important factors. I still haven't made a decision," said McMullin. He and Mindy Finn run the group "Stand Up Republic," which was formed to help gin up conservative opposition to the Trump administration.

McMullin's late developing, shoe-string presidential campaign didn't get anywhere. But he garnered 21.5 percent of the vote in Utah, where Trump was unpopular with Republicans, and succeeded in holding the president under 50 percent in a state that GOP nominees usually win with more than 60 percent.

Significantly, McMullin won 30 percent of the vote in Utah County, a key population center in the 3rd district. He finished second behind Trump there. That suggests that he could begin a Republican primary with a competitive base of support.

But Chaffetz's announcement has others considering a run as well. Chaffetz's 3rd district seat, stretching from the Salt Lake City area south and east, is reliably Republican, and an easy stepping stone to Washington for whomever emerges from the GOP primary.

State Sen. Deidre Henderson is another Republican being mentioned in Utah political circles as a potential formidable candidate. Henderson said in an email exchange with the Washington Examiner that she is interested in running.

"For years I've gotten questions about running when Jason steps away. I didn't expect to have to make this decision so soon," Henderson said. "I am overwhelmed by the volume of support and encouragement I have received since this morning's announcement. It's something my family and I are seriously considering."

Henderson previously worked for Chaffetz, which could make her an attractive successor to the congressman's supporters in the 3rd district. Chaffetz won re-election in 2016 with 73.5 percent of the vote.

Others mentioned as possible candidates include state Sen. Curt Bramble and state Rep. Mike McKell. McKell said in an email exchange that he has "no interest in running," but Bramble is considering it.

In a telephone conversation, Bramble said he has received encouragement from supporters and is "flattered" to be to be considered. Bramble offered no timeline for a decision.

Utah operates under a hybrid convention/primary nominating system. Candidates can choose to compete for the Republican nomination in a party convention that is heavily influenced by conservative activists. However, if any one candidate chooses to petition onto the traditional primary ballot decided by rank and file voters, the winner of the convention would be forced to compete in that primary contest.

The field of candidates is likely to take shape over the next 30 to 45 days.