Washington (CNN) -- The Veterans Affairs scandal's been a major issue on the campaign trail the past couple of weeks. Now it's front and center in the campaign ad wars.
Crossroads GPS, the non-profit sister organization to American Crossroads, a leading pro-GOP outside group which was co-founded and steered by Karl Rove, says that starting Wednesday it will start running a television commercial in Alaska that's critical of Sen. Mark Begich over his reaction to the growing controversy, which was first reported by CNN six months ago.
Begich is considered one of the most vulnerable Democratic senators running for re-election this year.
"A national disgrace. Veterans died waiting for care that never came. Senator Mark Begich sits on the Veterans Affairs Committee. His response? If there's a problem, they need to fix it. If there's a problem?" says the narrator in the spot, which is the first major ad to focus on the scandal.
"Four years ago, the VA's inspector general failed the Anchorage VA office in thirteen of fourteen areas. Now some Senators are blocking bipartisan legislation to shake up the VA and enforce accountability. Tell Senator Begich: when veterans are dying, it IS a problem," the narrator adds.
The group tells CNN that it will spend $450,000 to run the ad for one week. It's part of a $9.3 million late spring and summer ad buy announced last week by Crossroads GPS and American Crossroads (the super PAC) to run commercials in Alaska and three other crucial Senate races in Arkansas, Colorado and North Carolina. If the Republicans win back those four Democratic-held seats plus two more in this November's midterm elections, they would regain control of the Senate.
The Veterans Affairs controversy has mushroomed since CNN first reported last November on allegations of alarming shortcomings within the VA medical care system that potentially have had deadly consequences in dozens of cases.
The most disturbing and striking problems emerged in Arizona last month, with sources revealing to CNN details of a secret waiting list. According to the sources, at least 40 American veterans died in Phoenix while waiting for care at the VA there.
Veterans Affairs Secretary Eric Shinseki has come under pressure to resign from many Republican lawmakers and candidates, and even some Democratic senate and gubernatorial candidates. Shinseki said last week that he has not offered his resignation to President Barack Obama. The President last week made it clear he won't fire Shinseki – yet – but promised accountability.
Begich, who sits on the Senate Veterans Affairs' Committee, is expected to visit a VA facility in Anchorage on Wednesday. Alaska's junior senator is calling on the VA to address the wait times for veterans seeking medical care by filling vacancies at clinics with public health officers.
Begich, who was first elected to the Senate in 2008, has so far this cycle faced a flood of critical TV ads put up by another pro-GOP outside group, Americans for Prosperity, which is backed by the deep pockets of the billionaire industrialist brothers, David and Charles Koch.
Two weeks ago Crossroads reserved more than $5 million in ad time in Alaska from September 8 through October 26.
Earlier this cycle Crossroads went up with a spot in Alaska in support of former state attorney general Dan Sullivan, in his fight for the GOP nomination against Lt. Gov. Mead Treadwell and conservative Joe Miller, the 2010 Republican Senate nominee.
The VA scandal is also in a new ad attacking another vulnerable Democratic, Sen. Mark Pryor of Arkansas. The spot by Rep. Tom Cotton, the GOP challenger in the race, hits Pryor for what it says is his inaction in dealing with the controversy.
"What did Mark Pryor do? Nothing," says the narrator in the on-line ad.
The most recent polls indicate that the two-term senator leads the freshman congressman and Iraq War vet.
Democrats hold a 55-45 majority in the Senate (53 Democrats and two independents who caucus with the party), but are defending 21 of the 36 seats up in November, with half of those Democratic-held seats in red or purple states, like Alaska.