David and Charles Koch's groups will help in Alaska, New Hampshire and North Carolina. Dem groups counter Koch brothers

A collection of Democratic-aligned groups are launching a coordinated push in 2014 Senate races to counter heavy spending from the powerfully funded conservative organization Americans for Prosperity, Democratic strategists said Thursday evening.

The nonprofit Patriot Majority USA will begin airing TV ads over the next week in North Carolina and Arkansas, home to two highly competitive Senate contests that have seen considerable outside spending on the right. In a third race, the Alaska-based super PAC Put Alaska First will air ads defending Democratic Sen. Mark Begich from an ad campaign initiated by AFP.


Two other Democratic groups – Senate Majority PAC and the League of Conservation Voters – are already on the air in Iowa and New Hampshire, respectively.

( PHOTOS: Senators up for election in 2014)

Democratic anxiety about the 2014 midterm campaign has climbed in recent weeks, as polls have shown a growing list of incumbent senators facing difficult reelection fights amid a coast-to-coast spending blitz from AFP.

“The Koch Brothers are using an unprecedented amount of early money to flood these Senate races and try to buy the Senate,” said Ty Matsdorf, a strategist for Senate Majority PAC. “Democrats are going to continue to fight back against these attacks.”

Coordination among independent liberal groups has been critical to the party’s electoral strategy since the 2012 campaign, when an array of organizations – super PACs, unions, environmentalists and more – collaborated to offset spending on the right.

It is unclear whether groups defending Democratic control of the Senate will be able to match AFP and other conservative organizations, dollar for dollar, over the long run in the 2014 campaign. Up to this point, Senate spending in many states has tilted substantially toward the GOP.

( PHOTOS: Governors’ offices up for grabs in 2014)

Since the start of the year, AFP has spent millions attacking Democratic senators and Senate candidates in more than half a dozen states, focusing on Democratic support for President Barack Obama’s health care overhaul. The early intensity of the 2014 Senate air war is an illustration of the extent to which deep-pocketed independent groups have begun to eclipse traditional party committees in defining the battle lines in federal elections.

AFP spokesman Levi Russell said Democratic criticism of the group amounted to a diversionary tactic for politicians “unwilling to defend their support of Obamacare.”

“Rather than try to protect Americans who have lost their insurance or no longer able to see their doctor, they are hitting the panic button and lashing out at AFP to divert attention,” Russell said.

In its response ads, Patriot Majority USA will put $500,000 into defending North Carolina Sen. Kay Hagan and $300,000 behind Arkansas Sen. Mark Pryor.

The Alaska group backing up Begich is placing an initial buy of $50,000, essentially matching AFP over the first week on Alaska’s inexpensive airwaves.

While the content of these new ads has not yet been disclosed, pro-Democratic outside commercials already on the air have directly criticized AFP; the Senate Majority PAC ads in Iowa warned voters against trusting “out-of-state billionaires” attacking the Affordable Care Act.

In New Hampshire, LCV has wielded similar language against former Massachusetts Sen. Scott Brown, who is weighing a border-crossing challenge to incumbent New Hampshire Democrat Jeanne Shaheen.

Jeff Gohringer, a spokesman for the national environmental organization, said the group would ensure that Brown “won’t be able to hide from his record of defending Big Oil.”

“New Hampshire voters will see the same extreme agenda that the people of Massachusetts have already rejected,” he said in an email.