Two prominent environmental groups are going to bat early for their favored candidates in Colorado, FEC filings released late last week show. And given the prominence of environmental and energy issues in the state in recent years, investments from the League of Conservation Voters and the Defenders of Wildlife Action Fund could have a dramatic impact.

LCV, which has already ponied up serious money on behalf of Rep. Mark Udall's Senate bid along with a consortium of environmental groups, bought another $125,000 in television time, while the more political League of Conservation Voters Action Fund spent $10,000 in campaign literature on Udall's behalf. The expenditures come on top of $250,000 in television time and $12,000 in other expenses just this month.

LCV, Defenders of Wildlife, Clean Water Action and the Sierra Club are jointly targeting Senate races in New Mexico, New Hampshire and Colorado, where they see opportunities to win back Senate seats with environmentally-friendly candidates. The cooperation comes two years after the four worked together to oust California Republican Richard Pombo.

All four groups promised to go beyond those three Senate races, though, and have individually targeted other potential pickups. In Colorado, Defenders of Wildlife last week endorsed a former aide to Senator Ken Salazar, Betsy Markey, in her bid to unseat Republican Marilyn Musgrave and bought a whopping $200,000 in advertising time there. Markey has shown promise, raising $594,000 through the end of March and maintaining $376,000 in the bank.

Musgrave has had her troubles holding onto the district, as well. The three-term Republican won just 46% of the vote in 2006, winning by three points thanks to a third-party candidate, and took just 51% in 2004, as President Bush carried the seat by a wider 17-point margin. Still, she knows she will face a tough fight and has already raised an impressive $1.38 million, with just over $1 million on hand after March.

With environmental groups promising a real effort this year, Democrats may benefit from added emphasis on energy and climate change themes that have so far played a major role in the presidential race. Udall looks like the favorite, for now, in Colorado, while Markey may need more help. But if the groups are able to duplicate their success in Pombo's California seat, they may make a big difference.