WASHINGTON - Senate Minority Leader Mitch McConnell, R-Ky., is warning that the GOP may not win back control of the Senate in November's midterm elections - a cycle that typically would be favorable to the party not in power - as a political action committee linked to McConnell stages a rescue effort in the Ohio Senate race.

Asked Wednesday by reporters in Kentucky about his midterm predictions, McConnell said there's "probably a greater likelihood the House flips than the Senate."

"Senate races are just different, they're statewide, candidate quality has a lot to do with the outcome," he said, according to NBC News.

In a year when Republicans should have the advantage over Democrats, especially as President Joe Biden's approval ratings sag and inflation remains high, the GOP is facing surprisingly tight Senate races in several states - even with Republican groups providing huge sums of money to aid struggling candidates.

On Wednesday, the Cleveland Plain Dealer reported that the Senate Leadership Fund, a political action committee associated with McConnell, is investing $28 million in radio and television ads in Ohio in support of Republican Senate candidate J.D. Vance, who has been endorsed by former President Donald Trump.

The new pro-Vance ads will start rolling out after Labor Day, according to the newspaper, which noted the ad buy marks a significant increase from the estimated $5 million that national Republicans have invested in the Ohio race so far. In 2020, Trump won Ohio by about eight percentage points.

Still, polls have shown a remarkably close race between Vance, a venture capitalist and the author of "Hillbilly Elegy," and his Democratic opponent, Rep. Tim Ryan, as they vie for retiring Republican Sen. Rob Portman's seat. Vance's primary race was in part financed by billionaire Peter Thiel, who previously employed Vance at his venture capital firm. But Vance was outraised 4 to 1 by Ryan in the second quarter of 2022.

Ryan, a 10-term congressman who ran for president in 2020, is an experienced campaigner and moderate Democrat willing to break with party leadership on some policies, most notably trade and China.

In response to the GOP spending, Ryan tweeted, "If they're so focused on our race, that means we must be doing something right. Here's my message for Mitch McConnell, JD Vance, and the rest of the GOP: Bring it on."

Ryan also sent out a fundraising appeal alluding to the GOP investment and Florida GOP Gov. Ron DeSantis's campaign appearance Friday with Vance, writing, "National Republicans are PANICKING after *multiple* polls showed this race in a deadlock - and we're expecting DeSantis to attack me personally. This is the beginning of Mitch McConnell's new strategy to tear down my campaign."

Republicans need to gain one seat to capture the majority in a 50-50 Senate in which Vice President Kamala Harris is the tiebreaking vote. The significant investment in a GOP-leaning state for a Republican-held seat is surprising for the party 82 days to Election Day. And while the GOP is still favored to hold the Ohio seat in November, the close race is forcing the party to spend money defensively, funds that could otherwise be invested contesting Senate seats held by Democrats, such as Nevada and Colorado.

So far, the Senate Leadership Fund has also spent large amounts of money in the Georgia and Pennsylvania Senate races, investing $37 million and $34.1 million, respectively. But those races are considered more competitive for Republicans.

In Georgia, Republicans are seeking to unseat Sen. Raphael G. Warnock, D, whose victory in January 2021 helped Democrats achieve their narrow majority in the Senate. However, GOP candidate Herschel Walker - who has come under scrutiny for past falsehoods and the revelation of several children who had not previously been publicly disclosed - trails Warnock in the polls.

In the Senate race to replace retiring Pennsylvania Sen. Patrick J. Toomey, R, recent polls show Lt. Gov. John Fetterman, D, holding a double-digit lead over Republican nominee Mehmet Oz, a celebrity television doctor. Oz's campaign has spent much of the last week fending off attacks about how many houses he owns and withstanding online ridicule over a recently resurfaced video in which Oz botches the name of a local grocery store chain while supposedly buying ingredients for "crudités."

The spending by the McConnell-tied group comes as the National Republican Senatorial Committee (NRSC) is shifting its TV ad spending in several battleground states, canceling millions of dollars in ad reservations with plans to rebook the investments through coordinated spending with campaigns.

A Democrat who is tracking media buys, who spoke on the condition of anonymity to provide the data, said the NRSC this month has cut its TV ad reservations by more than $7 million in Pennsylvania, nearly $3 million in Arizona and more than $2 million in both Wisconsin and Nevada. Another Democrat tracking media buys confirmed similar numbers. The ad reservation changes were first reported by the New York Times earlier this week.

The shift comes as GOP Senate candidates in some of those states have lagged behind their Democratic opponents in fundraising, potentially hindering their ability to keep up on the airwaves and promote their own candidacies. In Wisconsin, meanwhile, Sen. Ron Johnson, R, raised about $7 million to Democratic nominee Mandela Barnes's roughly $2 million in the second quarter of the year, before Barnes's primary rivals dropped out.

This week, Barnes held a slight lead over Johnson, a Marquette Law School poll found.

Barnes has a 51% to 44% lead over Johnson in the poll, larger than Barnes's two-point margin in June. The poll has an error margin of plus or minus 4.2 percentage points.

Democrats see the Wisconsin race as one of their top opportunities to pick up a Senate seat.

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The Washington Post's Hannah Knowles contributed to this report.