(CNN) - Nearly 30 senators staged an overnight debate on the Senate floor Monday night through Tuesday morning, trying to bring attention to what they say is a dire need to combat climate change with legislative action.
But Sen. Mary Landrieu, the new chairman of the Senate Energy and Natural Resources Committee, was noticeably absent from the demonstration. The vulnerable Democrat faces re-election this fall in Louisiana, a state with large swaths of conservative voters.
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And Republicans aren't letting her absence go unnoticed.
The National Republican Senatorial Committee, which aims to get Republicans elected to the Senate, put out a new web video Tuesday, hitting Landrieu for allowing the talk-a-thon to take place, despite her chairmanship. The video also argues the senator doesn't stand up enough for American energy.
"We're tired of waiting," the ad's narrator argues. A large spinning wheel–the kind typically seen as a website is loading–whirls on a black screen throughout the 30-second video, trying to convey a sense of impatience.
CNN reached out to see if Landrieu had a comment on why she didn't go to the event, but her office did not give an immediate response.
Landrieu wasn't the only Democratic senator who skipped the all-night session. Sens. Kay Hagan of North Carolina, Mark Pryor of Arkansas and Mark Begich of Alaska–all vulnerable lawmakers up for re-election this year–also passed.
Climate change over the years has turned into an issue that few facing difficult re-election campaigns have wanted to touch.
When Democrats tried to pass legislation during President Barack Obama's first term that would have capped carbon emissions, skepticism around climate change reached an all-time high.
Opponents, led by organizations and businesses involved in the fossil fuel industry, successfully turned public opinion and stopped any efforts in its tracks.
But the tide appears to be changing.
According to Gallup, 41% now say that climate change is exaggerated - 7 percentage points lower than its high in 2010. And the number of those who say the seriousness of the issue is underestimated is on the rise.
In his second term, Obama has also pledged to take more executive actions to deal with climate change and dedicate more money to the issue.
CNN's Leigh Ann Caldwell contributed to this report.