Gov. Nathan Deal has endorsed state Sen. David Shafer in the Republican runoff for lieutenant governor.

Shafer faces former state Rep. Geoff Duncan of Cumming in Tuesday's runoff election.

Earlier this week Deal endorsed Lt. Gov. Casey Cagle in the race to succeed him as governor. Cagle faces Secretary of State Brian Kemp for the right to take on Democrat Stacey Abrams this fall.

In a statement, Deal said it was critical for the state to build on his administration’s accomplishments.

“The only way to ensure that occurs is by electing leaders who understand what it will take to build upon those efforts,” Deal said, calling Shafer a “strong and principled” conservative. “He has been a key legislative ally in my efforts to cut taxes and keep Georgia the No. 1 place to do business, and I believe he will continue moving Georgia forward.”

Duncan responded: “I respect Governor Deal, and he has served our state with honor. Career politician David Shafer and his campaign are in a free fall because voters want an outsider that will bring a fresh perspective to state government.

“David has all of the endorsements from elected officials. Good for him,” he said. “Republican voters want policy over politics under the Gold Dome, and David Shafer doesn’t represent that.”

Shafer, who has served in the state Senate for nearly 16 years, has racked up hundreds of endorsements from local, state and national politicians and organizations.

“I have been endorsed by virtually every person who has worked with both Geoff Duncan and me,” Shafer said. “They know our character, our work ethic, our leadership and our accomplishments.”

Shafer's endorsements range from dozens of state lawmakers, the National Rifle Association and Georgia Right to Life to Texas U.S. Sen. Ted Cruz and former state Sen. Rick Jeffares, the third-place finisher in the lieutenant governor's race.

The Duluth Republican also has far outraised Duncan in the campaign, raking in nearly $2.5 million as of June 30. Duncan reported raising about $958,000.

An Atlanta Journal-Constitution/Channel 2 Action News poll released last week showed Shafer with a slight lead over Duncan.

According to the poll, 34.4 percent of likely Republican voters said they would vote for Shafer, compared with 31.4 percent who said they would vote for Duncan. About one-third of voters said they were undecided.