Former governor Ted Strickland, the Democratic nominee for the Senate in Ohio, speaks in Columbus, Ohio, on June 21. National Democrats are delaying a major ad buy amid growing concerns that Strickland is running a lackluster campaign and their chances of flipping the Ohio seat could be slipping away. (Jay LaPrete/AP)

The Democratic Party’s top committees focused on winning Senate races canceled more than a week of television ads that were set to run next month in the key battleground of Ohio, where former governor Ted Strickland (D) has struggled to gain traction against incumbent Sen. Rob Portman (R).

The Democratic Senatorial Campaign Committee had reserved advertising time on Ohio TV stations starting Sept. 13. Now, according to political ad trackers in both parties, the national Democrats won’t launch that campaign until Sept. 22. The Senate Majority PAC, a super PAC with ties to Democratic leaders prohibited from directly coordinating with the DSCC or candidates, has also dropped its advertising plans for a similar period.

The DSCC has not withdrawn its support from Strickland entirely — the committee is currently funding a Strickland campaign ad through its limited coordinated-spending accounts that seeks to tie Portman to GOP presidential nominee Donald Trump — but the delay in unleashing ads from the committee’s more substantial independent expenditure arm comes amid rising doubts about Strickland’s viability against Portman.

Strickland campaign spokesman David Bergstein said the delay represented a shift in tactics, not a vote of no confidence from party honchos in Washington.

“The DSCC is spending the same amount of money they were slated to spend, it’s just being used to help fund our existing ad instead of through an independent expenditure,” Bergstein said.

Said Sadie Weiner, the DSCC’s communications director, “We’re proud to support Ted’s campaign in a variety of ways, including with the ad buy we are funding right now featuring an ad with important information about Trump and Portman and their dangerous positions on women’s health.”

Super PAC officials were more blunt about its decision, citing it as a move to best position money in order claim the five seats Democrats need to take back the majority in November. “We regularly adjust strategy to maximize our resources and make sure we’re in the best possible position to win back the majority,” Shripal Shah, spokesman for Senate Majority PAC, said in a statement.

Democrats will need just four seats to win the majority if Hillary Clinton defeats Donald J. Trump for the presidency, and in every simulation of the Senate battleground last fall, Ohio was expected to be a battle until the very last day.

This week’s moves by Democrats spurred chatter among Republican strategists that national Democrats were abandoning Strickland, whose campaign has been pummeled by a relentless barrage of ads from Portman that disparaged his tenure as governor last decade.

The DSCC’s decision, which nixed about $500,000 worth of advertising, is by no means final. Party committees sometimes take pauses to see whether their candidate can gain more traction and thus make another investment in the race worthwhile.

The super PAC nixed an expected run of ads from Sept. 6 to Sept. 20, according to Democratic and Republican officials. GOP strategists watching advertising buys said they’ve seen Majority PAC ads canceled in critical battlegrounds of the Columbus and Dayton media markets.

The drawdown by Senate Majority PAC was first reported Tuesday by The Hill.

Establishing name identification across the massive state of Ohio can cost upward of $10 million in advertising, so Strickland was hailed early on as one of the DSCC’s best recruits of the cycle because the former governor was more well known than Portman as this year began.

But Strickland has struggled to raise the requisite funds to keep pace with Portman. By July 1, Portman had raised more than $15 million, the most of any endangered incumbent in the Senate, and he headed into the home stretch of the campaign with a war chest of $13.2 million.

Strickland had raised $7.1 million and began the final months of the campaign with a fraction of Portman’s resources, just $3.7 million.

The incumbent has leveraged that edge by defining Strickland as the governor who lost more than 350,000 jobs in his single term in office, with the ad broken down by region to show how many jobs were lost in certain regions of the state.

Strickland recently tried to rebut that with his own ad in which he repeats the allegation: “They say I lost jobs and drained the rainy-day fund,” the ex-governor says to the camera, then going into a lengthy explanation of the state’s dire straits during the Great Recession.

Some Democrats in Washington privately bemoaned the Strickland ad for repeating Portman’s allegation.

According to RealClearPolitics summary of public polling, Strickland has not held any lead in the race against Portman since early May. In the past five public polls, Portman’s lead has ranged from 5 percentage points to 15.

Philip Rucker contributed to this report.