Muckraker: Grist on PoliticsIn the past 24 hours alone, more than $130,000 has been spent by independent groups in support of Barack Obama, and of that, $38,024 was spent by the League of Conservation Voters, accounting for the second-largest expenditure by a single independent group in favor of Obama in the final day before people head to the polls.

LCV also spent $27,540 against McCain — putting them atop the list of those dropping cash on anti-McCain efforts, according to the Center for Responsive Politics.

“LCV’s been working all year to elect pro-environmental candidates, at every level of government, and here in the final push we’re putting every resources possible in the field to let voters know where these candidates stand on global warming, on clean energy, and on clean air and water,” Josh McNeil, press secretary for the League, told Grist today. The funds have paid for workers to go door-to-door talking to voters, television ads, and mailers, McNeil said.

McNeil said the group knocked on 40,000 doors in Virginia, Colorado, and New Hampshire over the past weekend alone, and since last Wednesday had contacted 130,000 voters over the phone.

The Center for Responsive Politics is keeping track of all last minute expenditures by independent groups — also known as Political Action Committees or PACs — for and against political candidates, which offers some fascinating insight into the end-run for Election Day. PACs are legally required to report expenditures totaling more than $1,000 to the Federal Elections Commission within 24 hours. They offer figures on the spending by particular groups in the past 24 hours, week, and throughout the election cycle.

Defenders of Wildlife Action also dropped $394 on advertising for Obama over the past 24 hours, making them the 13 highest spender in support of Obama in this the final day before the election and the only other environmental group to list an expenditure in the past day.

Some of the biggest spenders on Obama in this election cycle? A number of environmental groups rank high on the list of expenditures — up among large labor groups, the National Rifle Association (who was spending cash against Obama), and general liberal PACs like MoveOn.

Environment America Inc. spent $1,130,950, the 9th largest expenditure for Obama, and Environment California spent $660,136, making them the 10th biggest spender in favor of the Democrat. Sierra Club came in 12th, spending spent $589,818. The League of Conservation Voters spent $545,827 via two separate committees, which combined would make them the 14th biggest spender on ads and other efforts in support of Barack Obama this year.

Environmental groups were also among the biggest spenders against John McCain. Defenders of Wildlife spent $636,231 against the Republican ticket, ranking them 7th highest spender against McCain. The Sierra Club spent $632,212, putting them at No. 8 on the list. LCV came in 9th at $429,908.