Larry Hogan, left, the Republican nominee for governor of Maryland, and Anthony G. Brown, the Democratic nominee.

The Democratic Governors Association plans a hefty purchase of television ads in coming weeks to bolster Maryland Democratic gubernatorial nominee Anthony G. Brown in his campaign against Republican businessman Larry Hogan.

The $750,000 in spending, confirmed Tuesday night by several people familiar with the ad purchases, suggests that the Democratic Party is bracing for a more competitive race in the heavily Democratic state than early polls suggested.

DGA spokesman Danny Kanner said the organization, which helps elect Democrats across the country, was “committed to ensuring Maryland remains a blue state, and that Anthony Brown is elected governor.” Brown, the state’s lieutenant governor, is seeking to succeed Gov. Martin O’Malley (D).

Multiple people put the size of the buy at about $750,000 and said ads have been reserved on Baltimore network affiliates and cable stations through Oct. 1.

Kanner said that the DGA money is flowing through an independent arm of the organization and that he was not privy to the nature of the ads.

The Hogan campaign said the DGA spending is evidence that Hogan has a real shot at upsetting Brown in a state where registered Democrats outnumber Republicans more than 2-to-1.

Brown is “desperately turning to what will undoubtedly be attack ads by the Democratic Governors Association in an attempt to rescue his badly faltering campaign,” said Hogan spokesman Adam Dubitsky.

Brown campaign manager Justin Schall said the organization’s investment in the state reflects the “historic” nature of the election, “not only for Maryland but for the country.”

If Brown prevails in November, he would be the first African American governor of Maryland and only the third elected in the country.

“I think the DGA understands the importance of electing Anthony Brown and the horrible direction Larry Hogan would take the state,” Schall said.

Hogan also is getting help from Republicans outside Maryland. New Jersey Gov. Chris Christie, the chairman of the Republican Governors Association and a possible 2016 presidential candidate, is scheduled to appear with Hogan at a Sept. 17 event in Bethesda.

Money raised at the event will benefit the Maryland Republican Party’s efforts to promote Hogan’s candidacy.

Outside help could prove essential to Hogan’s bid because he has elected to participate in the state’s public financing system, which limits direct spending by his campaign to about $2.6 million.

As of late last month, Hogan reported having about $2.4 million in the bank, all of that from a state grant.

Brown and his running mate reported having more than $760,000 in the bank. But unlike Hogan, Brown’s campaign is not subject to a cap on its spending and has a full slate of fundraisers lined up in coming weeks.

Jenna Johnson contributed to this report.