A coalition of environmental groups launched a seven-figure advertising campaign Monday in a handful of Senate battleground states, supporting candidates who back “clean energy and clean air policies” and kicking back at energy interests that oppose more muscular environmental regulation.

The advertising and grass-roots organizing effort by a confederation of green groups — including the Environmental Defense Fund and the Sierra Club — is the opening salvo of an effort in 11 states to counter the impact of American for Prosperity and other well-funded conservative groups attacking renewable energy and regulatory programs.

American for Prosperity, backed by industrialists David and Charles Koch, has already run advertisements targeting several of the candidates being defended today by the environmental groups.

Since late 2013, AFP has spent nearly $30 million on ads in key Senate races.

This year, most of the attacks from AFP have criticized candidates for supporting the health-care overhaul backed by President Obama.

Charles and David Koch are hated by Democrats and loved by Republicans. But regardless of which party you support, there's almost no question that the Koch Brothers have made money off of you. (Jeff Simon,Daron Taylor/The Washington Post)

Sen. Kay Hagan (D-N.C.) has faced a withering attack from AFP, mostly over her support for the Affordable Care Act.

The groups’ North Carolina ad, which starts airing Monday, targets unnamed “oil industry billionaires” for attacking Hagan over her support for “common sense air quality protections.” The Democratic candidate for Senate in Michigan, Rep. Gary Peters, will be the beneficiary of ads running Monday that are sponsored by organizations in the coalition. Peters also has seen attacks from AFP as he faces Republican Teri Lynn Land in a race to succeed retiring Democratic Sen. Carl Levin.

The environmental groups are launching similar issue ads Monday on behalf of another Democratic House member hoping to take over after the retirement of a long-serving political icon: Rep. Bruce Braley of Iowa, who hopes to succeed Democratic Sen. Tom Harkin. The ads airing in Des Moines on Monday tout Braley’s record promoting wind energy. Separately, the Sierra Club will sponsor a digital advertising campaign on the same theme that starts Monday in Iowa.

Groups in the coalition are also backing a Republican in this first round of ads: Sen. Susan Collins, who is favored to win reelection from Maine.

In this year’s midterm elections, environmentally inclined lawmakers have been promised support from Tom Steyer, a billionaire West Coast investor, and the organization NextGen, which has pledged to raise $100 million in 2014. But NextGen has suggested it may condition support based in part on a candidates’ willingness to oppose the Keystone XL Pipeline, which would carry oil sands from Canada to the Gulf Coast. Hagan supports the pipeline and therefore might not be able to count on help from Steyer. But other environmental groups are making clear that they will be there for Hagan, recalling her support for measures to curb mercury and other power plant emissions.

“We want to thank these lawmakers for providing strong leadership,” said Elizabeth Thompson, vice president of climate and political affairs for the Environmental Defense Fund. In addition to the EDF and the Sierra Club, the new campaign is backed by other national and regional groups, including the Southern Alliance for Clean Energy. These groups will join with a broader coalition of groups that have backed clean-air standards in the past to take action in seven other battleground states in the weeks to come.

“This is the opening salvo,” said David Di Martino, a communications adviser to the coalition. “If you stand for clean energy, we will stand with you.”