WASHINGTON — Ohio primary voters selected establishment candidates on Tuesday for the next big test of the Democrats’ promised “blue wave,” a House special election this August in the suburbs of Columbus that could indicate just how strong Democrats will be in November with college-educated, affluent voters.
After winning a six-way primary in central Ohio on Tuesday, Danny O’Connor, 31, a Franklin County official, will ask voters to send him to Congress on Aug. 7 to fill the House seat vacated by a long-serving Republican, Pat Tiberi.
The special election, which will take place 13 weeks before Election Day, will offer clues of Democratic strength, particularly on the kind of suburban terrain that will be critical in numerous races this fall as Democrats try to oust Republicans from control of the House.
Mr. Tiberi’s seat in the Columbus area has hardly been a swing district: It has been in Republican hands since 1983, when his predecessor, John R. Kasich, now Ohio’s governor, began his first term. But Democratic candidates in special elections for vacant House seats in more forbidding territory — including Arizona, southwestern Pennsylvania and South Carolina — have performed strongly since President Trump’s inauguration. And the makeup of the Ohio district suggests it could be fertile ground for a competitive — and expensive — race.
Almost all the recent special House elections in Republican seats have built up steam until an Election Day that has garnered remarkable attention, even in seats where the Democrat had little shot. The Tiberi seat is likely to be no different.
“If I was the Republican Party, I’d be pretty concerned about it,” said Representative Tim Ryan, Democrat of Ohio. Voters were fond of Mr. Tiberi, he said, but he predicted that Mr. O’Connor could win over people repelled by the “constant chaos” and “demeaning nature” of the Trump presidency.
Mr. O’Connor — who is the Franklin County recorder, an elected position that handles real estate records — will face Mr. Tiberi’s preferred successor, Troy Balderson, a Republican state senator who narrowly emerged from a nine-way primary on Tuesday. Mr. Balderson, 56, squeaked by Melanie Leneghan, a township trustee who was backed by Representative Jim Jordan of Ohio, a founder of the conservative House Freedom Caucus. Some Republicans had worried Ms. Leneghan’s ardent brand of conservatism would have made her particularly vulnerable in the special election.
Representative Steve Stivers of Ohio, the chairman of the National Republican Congressional Committee, invoked the woman Republicans love to run against, Representative Nancy Pelosi of California, the Democratic leader.
“I just saw the opposition research book on Danny O’Connor, and he is a classic liberal,” Mr. Stivers said on Wednesday. “He might say he’s not going to vote for Pelosi. Maybe she’s not liberal enough for him.”
The Democratic Congressional Campaign Committee was noncommittal about its plans even as it was taking a shot at the Republican candidate. A spokesman for the committee, Jacob Peters, said “the D.C.C.C. will continue to assess” the contest.
But he said, “The reality is that Troy Balderson is a heavily damaged nominee who just spent a lot of time and money to make the case that he is the greatest threat to Medicaid and health coverage for central Ohio families.”
Mr. Tiberi, who left Congress to become president of the Ohio Business Roundtable, won his last re-election bid by a more than two-to-one ratio. The district, Ohio’s 12th, includes the Republican stronghold of Delaware County, which has not voted for a Democrat for president since Woodrow Wilson in 1916. Mr. Trump won the district in 2016 by 11 percentage points, and on Tuesday, considerably more people cast votes in the Republican primary than in the Democratic primary.
Still, recent special elections offer reason for Democrats to be optimistic. In Arizona last month, a Democrat mounted an unusually strong challenge, albeit an unsuccessful one, in a district that Mr. Trump won by more than 20 percentage points. The month before, another Democrat, Conor Lamb, won a special election in Pennsylvania in a district that Mr. Trump carried by nearly 20 points.
At 33, Mr. Lamb is not much older than Mr. O’Connor. And like Mr. Lamb, Mr. O’Connor said he would not support Ms. Pelosi.
“I think we need a wholesale change in leadership on both sides,” Mr. O’Connor said in an interview on Wednesday.
Mr. O’Connor described himself as a pragmatist focused on issues like health care and the economy. He did not leap at the chance to critique Mr. Trump’s presidency, though he pushed back on Mr. Trump’s promised wall along the border with Mexico.
“I’d rather spend money rebuilding bridges in Ohio than building a wall in Texas,” he said. By contrast, Mr. Balderson pledged in a campaign ad to “use conservative grit to build the darn wall.”
The Balderson campaign signaled that Ms. Pelosi would be a central figure in the contest, a tactic Republicans used against Mr. Lamb.
“Danny O’Connor and his Nancy Pelosi agenda are just completely out of step with the voters in this district,” said Brad Shattuck, a strategist for the campaign.
“Troy is a conservative who wants to go up there and get something done,” Mr. Shattuck said. “And I think that juxtaposes with someone who just wants to go up there and support Nancy Pelosi and her agenda.”
The district’s significant suburban population — with many affluent, college-educated voters — will make it a noteworthy test case in the run-up to November. Among Ohio’s 16 congressional districts, it has the highest median household income and the highest percentage of adults with a bachelor’s degree or higher.
“There’s definitely an opportunity for there to be kind of a Trump backlash in this district,” said Kyle D. Kondik, an analyst at the University of Virginia Center for Politics, who wrote a book about Ohio’s presidential voting history. He said it was the kind of district filled with Republicans who might think that someone like George W. Bush, Mitt Romney or Mr. Kasich “is a better fit for their sensibilities” than Mr. Trump.
But Mr. Kondik cautioned, “I still think you’d rather be the Republican in this district.”
The winner of the special election will not have much job security. Mr. O’Connor and Mr. Balderson each won two separate primaries on Tuesday, one for the special election and one for the general election in November. Regardless of the outcome in August, both candidates will appear on the ballot again in November when voters choose a representative for a full two-year term.