ATLANTA — A politically untested businesswoman is expected to be appointed this week to a soon-to-be-vacated United States Senate seat in Georgia, a move that would pit the state’s governor against President Trump, who had lobbied for a different candidate.
The choice of the business executive, Kelly Loeffler, to fill the seat set off alarm bells among Mr. Trump’s most ardent defenders and was seen by political observers as an attempt by Brian Kemp, the governor, to shore up Republican support from suburban women.
The decision, confirmed on Monday by a Republican congressional staffer who requested anonymity because the choice had not been made public, also reveals an intraparty rift over the best way to maintain Republican dominance in Georgia.
Mr. Kemp’s choice was earlier reported by other publications, including The Atlanta Journal-Constitution, which said Mr. Kemp was expected to announce his decision on Wednesday morning.
The reports were swiftly criticized by Mr. Trump’s supporters. On his website, the Fox News host Sean Hannity called Ms. Loeffler a “centrist businesswoman” whose appointment could “seriously harm the White House’s efforts to end the Democrats’ ongoing Ukraine hearings and other pointless investigations.”
On Twitter, Mr. Hannity urged conservatives to call Mr. Kemp, asking, “Why is he appointing Kelly Loeffler?”
The Senate seat is being vacated at the end of the year by Johnny Isakson, a Republican who is experiencing health problems. Cody Hall, a spokesman for Mr. Kemp, declined to comment on Monday.
But political observers in the state interpreted Mr. Kemp’s pick as an effort to shore up the party’s support among suburban women, in anticipation of a primary election to fill the Senate seat in November. Ms. Loeffler would serve until then, allowing her to run for the final two years as an incumbent.
Brian Robinson, a communications consultant who previously worked for Nathan Deal, the state’s former Republican governor, noted that Mr. Kemp, who ran as a shotgun-brandishing Trumpist candidate in 2018, struggled to win over such women in his narrow victory last year over Stacey Abrams, the Democratic candidate.
“The governor obviously thinks that having a metro Atlanta woman will help bring back some of those college-educated white women we lost in 2018 in big numbers,” Mr. Robinson said. “So strategically, he’s trying to build a coalition that can turn out the Trump-slash-Kemp base while bringing back some of the folks we’ve lost.”
Republican disagreements over the pick surfaced late last month when The Wall Street Journal reported that Mr. Trump had met with Mr. Kemp and Ms. Loeffler in a “tense” meeting at the White House, in which Mr. Trump said Mr. Kemp would be taking a risk by appointing Ms. Loeffler.
Mr. Trump, the newspaper said, prefers Representative Doug Collins, the top Republican on the House Judiciary Committee and a reliable ally of the president. Mr. Collins would ostensibly continue to support Mr. Trump if appointed to the Senate, which would vote on whether to remove the president from office if he were impeached by the House.
But also at issue is how Republicans should best approach a state like Georgia in 2020, and whether Mr. Trump’s focus on turning out his base will be enough to ensure victory for both the president and down-ticket Republican candidates.
Mr. Kemp largely followed Mr. Trump’s base-turnout strategy in the governor’s race, taking a hard-line stance on topics like gun rights and immigration. In one of his ads, he vowed to personally deport, in his truck, those in the state who were not living there legally.
Mr. Trump — who won Georgia by five percentage points — endorsed Mr. Kemp in last year’s Republican primary, elevating his underdog candidacy, and campaigned for him in the general election, which Mr. Kemp won by less than two percentage points.
The results left many Republicans worried that Mr. Trump’s sex scandals and boorish style had alienated female voters, particularly in the vote-rich suburbs north of Atlanta that for decades has been a reliably Republican area.
Lucy McBath, a Democrat, won a close race last year in the state’s suburban Sixth District, and in the neighboring Seventh District, Rob Woodall, the Republican incumbent, eked out a victory against a Democratic challenger.
Those results came as the state is undergoing intense demographic changes — it could turn majority-minority within a decade — that may benefit Democrats.
Ms. Abrams, who had hoped to become the state’s first black female governor, has accused Mr. Kemp, the former secretary of state, of disenfranchising minority voters and supporting policies that amount to voter suppression; in April, she referred to him as a “cartoon villain.”
While Mr. Kemp has appeased his conservative base by signing a law that in effect bans abortion after six weeks of pregnancy, he has also followed a time-honored tradition among Republican governors in Georgia by tacking center, particularly with his diverse appointments to top state positions.
Ms. Loeffler is the chief executive of Bakkt, a financial services firm, and a co-owner of the Atlanta Dream, the Women’s National Basketball Association franchise. She could not be reached for comment on Monday.
Conservative critics have said she is overly centrist, citing her support of Senator Mitt Romney of Utah, the former presidential candidate. Marjorie Dannenfelser, president of the anti-abortion Susan B. Anthony List, has criticized her for sitting on the board of Atlanta’s Grady Hospital, which Ms. Dannenfelser, in a tweet, called “an abortionist training hub.”
Mr. Kemp dismissed the criticism, saying on Twitter, “The idea that I would appoint someone to the U.S. Senate that is NOT pro-life, pro-2nd Amendment, pro-freedom, and 100% supportive of our President (and his plan to Keep America Great) is ridiculous.”
The November 2020 election for the Senate seat will be a jungle-style primary, meaning that all candidates from all parties would run against each other.
Matt Lieberman, a Democrat and the son of former Senator Joe Lieberman, has announced his candidacy, and the race could eventually attract other high-profile Democratic contenders. Those include Jen Jordan, a state senator whose passionate speech opposing Georgia’s abortion law went viral this year, and Michael Thurmond, the chief executive of populous DeKalb County, who in 1998 became the first non-incumbent African-American to be elected statewide.
But the Republican side is also far from settled. In an interview on “Fox News Sunday,” Mr. Collins, whose Ninth District covers northeast Georgia and who is considered one of the most conservative members of the House, left open the possibility of jumping into the Senate race.
“We’ll have to see where the governor goes with this pick,” he said, “and then we’ll have a decision to make.”