On the same day the U.S. Senate soundly rejected Sen. Mitch McConnell’s bill to speed up the permitting process for oil companies, Democratic leadership and environmental groups have embarked on a contentious path.

On Thursday the Senate voted 57-42 against the minority leader’s plan to allow more Coastal oil and gas exploration, and to speed the issuance of drilling permits to oil companies. Yet, while Republicans were left to lick their wounds after McConnell’s defeat, it was Democrats who were inflicting wounds on themselves.

Majority leader Sen. Harry Reid (D-Nev.) has gone public with his displeasure with several environmental organizations that have become increasingly angry with Democrats who vote against environmental protections. At first, Reid remained quiet following the League of Women Voters criticism of Sen. Claire McCaskill (D-Mos.) for her votes last month to postpone EPA climate regulations for two years. But after the head of the Sierra Club tweeted angrily about other Democrats' votes to keep tax breaks in place for the big five oil companies, Reid broke his silence.

“I think whoever this is in the Sierra Club had better get his facts right. I don’t buy the illogic of the tweet,” the majority leader said in a Las Vegas Sun report. Reid’s comments came after he, a few other Democratic senators, and the leaders of the Center for American Progress, Environment America, the Natural Resource Defense Council and the National Wildlife Federation all met on Capitol Hill. Other than Reid, none of those in the meeting made any specific comments about the infighting within the liberal camp.

Beyond McCaskill’s vote last month, this week Democrats Mary Landrieu of Louisiana, Mark Begich of Alaska and Ben Nelson of Nebraska all voted to allow the big five oil companies to continue to take government subsidies despite being some of the most profitable companies in the world. Landrieu, Nelson, Begich and McCaskill are all up for reelection in 2012.

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