OKLAHOMA CITY — Democrat Kendra Horn surprised even her own supporters in 2018 when the first-time candidate eked out a victory in an Oklahoma City congressional district that had been in Republican hands for nearly four decades and had voted heavily for Donald Trump in 2016. But now the impeachment drive against the president has put her and others like her in a tight spot.

She opposes an impeachment inquiry at this time, Horn spokeswoman Chacey Schoeppel said Thursday, but she will listen to the facts and “go through them methodically.”

As of Friday morning, an Associated Press survey of most of the House Democrats showed six as either not supporting or undecided on the inquiry that was announced this week by House Speaker Nancy Pelosi. The six represent an extraordinarily small share of the 235 Democrats in the House. And Pelosi doesn’t need them to move ahead with an investigation.

But they illustrate the insecurities of those Democrats who managed to get elected from Trump country.

All the holdouts hail from districts that Trump won handily in 2016 and that the Republicans are targeting as they try to win back the House in 2020. Most of the six weighed in after the explosive whistleblower complaint against the president became public Thursday.

Horn’s margin of victory in 2018 was just 1.4 percentage points in a district that Trump won by nearly 14 points.

“She’s a smart politician. That’s why she’s being cautious,” said University of Oklahoma political science professor Keith Gaddie. “Horn’s seat is the No. 1 most competitive Democrat-held district in the U.S. right now.”

Other Democrats who have joined Horn in opposing the impeachment inquiry into the president’s attempt to enlist Ukraine in digging up dirt on his rival Joe Biden are Reps. Collin Peterson of Minnesota and Anthony Brindisi of upstate New York. Democrats who responded to the AP as “undecided” were Reps. Jared Golden of Maine, Ben McAdams of Utah and Xotchitl Torres Small of New Mexico.

“I think we have allegations and news reports right now, and I’m not going to jump to any conclusion until all the facts come out,” said Brindisi, whose district Trump won by 16 points.

Torres Small has had to walk a fine line in her sprawling district in New Mexico’s border region, which has traditionally voted Republican.

“Xochitl Torres Small has to be careful not to be painted as a liberal Democrat who just signs on to anything that let’s say Nancy Pelosi supports,” said veteran pollster Brian Sanderoff. “She exhibits caution, which is smart politically and probably more reflective of at least half of her district.”

Collin Peterson, the lone Democrat in Minnesota holding out against the impeachment push, called the process a waste of time. He has represented a huge swath of northwestern Minnesota for nearly 30 years, and his powerful position as chairman of the House Agriculture Committee adds to his appeal to the district’s rural and agricultural base. Trump won Peterson’s district by 30 points.

“If anyone thinks a partisan impeachment process would constrain President Trump, they are fooling themselves,” Peterson said in a statement. “Without significant bipartisan support, impeachment proceedings will be a lengthy and divisive action with no resolution.”

McAdams, a moderate Democrat who flipped a suburban Salt Lake City district in deeply conservative Utah last year, said Thursday he wants more information before deciding on whether to support impeachment proceedings.

Rep. Conor Lamb, a freshman whose Pennsylvania district stretches from some wealthy Pittsburgh suburbs through hardscrabble steel towns, initially was “undecided” on a formal impeachment inquiry but shifted Friday and issued a statement that avoided the words “impeachment” and “Trump.” Trump won Lamb’s district in 2016, but it has since been redrawn.

“Congress must continue our work to get the truth,” Lamb read. “I fully support the House Intelligence Committee’s inquiry, and I believe that at each step of the way we must follow the evidence where it leads.”