(CNN) -- Gun control supporting candidates facing tight races for governor in Connecticut and Maryland are the beneficiaries of a last-minute ad buy from former New York City Mayor Michael Bloomberg.

Bloomberg's group, Independence USA PAC, is supporting pro-gun control candidates like Democratic Gov. Dan Malloy in Connecticut and Democratic Lieutenant Governor Anthony Brown in Maryland, both of whom are locked in tight races to lead their states.

Gun control is a "simmering issue" in these states, said Bloomberg spokesman Stu Loeser. Historically, the PAC has donated to both Democrats and Republicans supporting "common sense" gun control in an attempt to stave off the gun lobby and tie pro-gun candidates to the National Rifle Association.

In Connecticut, the group hopes that support for gun control will emerge as a salient theme for voters in the wake of the state's Sandy Hook massacre in December 2012, where 20 young children and 6 adults were shot and killed at an elementary school. The newest ads there target Malloy's opponent, Republican challenger Tom Foley.

"The NRA praises Tom Foley, calling him pro-gun," a voice in a new Connecticut ad says. "No wonder. The NRA opposes comprehensive background checks. And Foley promised he'd sign a bill to weaken them, undermining our gun safety laws."

The Foley campaign did not immediately return CNN's request to respond to Bloomberg's efforts.

This is the second ad buy in Connecticut in the past week: Television watchers also might have noticed another gun control ad which launched Friday from the group. Loeser said these ad buys represent an attempt to make sure gun control stays on the agenda in these states.

"The public safety bills that were passed in the wake of the Sandy Hook massacre -- which have overwhelming support -- are an issue for discussion," Loeser said. "One of the things that Independence USA is able to do is help highlight issues particularly in expensive media markets like New York City that might otherwise get swept under the rug."

The group has plans to spend $1.7 million in the state in its support for Malloy, who signed a gun control law in 2013 which expanded background checks and banned sales of some weapons like the AR-15 semiautomatic rifle, which was used in the Sandy Hook massacre.

Foley took a stand against Malloy's measures in an August gubernatorial debate, calling his moves "grandstanding" and "overreaching." He has also said he would repeal Malloy's gun control legislation.

Four years ago, Malloy narrowly fended off Foley by less than one percentage point in their 2010 battle for the governor's office. The candidates are tied in the most recent poll from CBS/New York Times/YouGov.

In Maryland, Brown holds a substantial lead over his opponent, Republican Larry Hogan. But the race has drawn the attention of national headliners: Republican New Jersey Gov. Chris Christie has stumped in the state for Hogan, while top Democrats like President Obama and the Clintons have appeared for Brown.

Bloomberg -- a noted philanthropist and media magnate boasting a net worth of $34 billion -- has pledged to spend $25 million through his political action committee to raise awareness on gun control across the country. Shortly after the Newtown shootings, he made a sizable donation to Americans for Responsible Solutions, a fundraising group run by former Rep. Gabrielle Giffords. The former congresswoman survived gun wounds to her head after an attempted assassination attempt in January 2011.

With polling places officially open in Connecticut and Maryland in just a week, Bloomberg's group is focused on Election Day.

"We take these elections one at a time," Loeser said.