Republican Ron Estes, the Kansas state treasurer who narrowly slid to victory Tuesday night in the state's special House election, could already be facing a primary challenge for next year, the Wichita Eagle reported Wednesday.

Sources told the newspaper that state Senate President Susan Wagle, a Republican, is weighing a U.S. House bid in 2018. Wagle is considered a heavyweight among Kansas Republicans and could put up a potentially tough primary challenge for Estes.

"The lack of enthusiasm from Republicans in yesterday’s election was disconcerting," Wagle’s chief of staff, Harrison Hems, told the Wichita Eagle. "Susan is focused on serving Kansans as Senate president, but will continue to evaluate how she best serves in the future."

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Estes defeated Democratic challenger James Thompson to fill the House seat of CIA Director Mike Pompeo, who previously served as the representative from Kansas's 4th District.

The district has long been considered safe for Republicans, but Estes won the special election by only 7 points — a small margin for a GOP candidate there. Republicans became worried about the race in its final weeks, and his campaign received a last-minute boost from high-profile Republicans, including Sen. Ted Cruz Rafael (Ted) Edward CruzLoeffler calls for hearing in wake of Netflix's 'Cuties' Health care in the crosshairs with new Trump Supreme Court list 'Parks and Rec' cast members hosting special reunion to raise money for Wisconsin Democrats MORE (R-Texas), President Trump and Vice President Pence.

Cruz made an appearance in the district on Monday, and Trump and Pence separately recorded robocalls urging Republicans in the state to vote for Estes.

Estes told the Wichita Eagle on Wednesday that he hadn't heard anything about a possible primary challenge from Wagle and said he was not yet thinking about his reelection bid next year.

"Right now, I haven’t even been sworn in yet," he said. "I’m focused on doing the job. That’s the big thing right now."