WASHINGTON -- The leading sponsors of a long-delayed energy and climate change bill said Friday they will press ahead despite losing the support of their only Republican partner, Sen. Lindsey Graham.

Sens. John Kerry, D-Mass, and Joe Lieberman, I-Conn., said they plan to introduce a bill on Wednesday. The pair made the announcement just hours after the South Carolina Republican said it's impossible to pass the legislation now because of disagreements over offshore drilling and immigration reform.

Graham has been negotiating with Kerry and Lieberman for months but said Friday that he doubts the climate bill has much chance of success.

"Regrettably, in my view, this has become impossible in the current environment," Graham said in a statement. "I believe there could be more than 60 votes for this bipartisan concept in the future. But there are not nearly 60 votes today, and I do not see them materializing until we deal with the uncertainty of the immigration debate and the consequences of the oil spill."

Sixty votes are required in the Senate to overcome filibusters.

Kerry and Lieberman said they plan to introduce the bill Wednesday. "We are more encouraged today that we can secure the necessary votes to pass this legislation this year in part because the last (few) weeks have given everyone with a stake in this issue a heightened understanding that as a nation, we can no longer wait to solve this problem which threatens our economy, our security and our environment," Kerry and Lieberman said.

Last month, Graham threatened to withhold his support for the climate and energy legislation because he was angry that Democrats said they would take up a rewrite of immigration policy. Kerry and Lieberman postponed the long-awaited unveiling of the legislation, which aims to cut emissions of carbon dioxide and other greenhouse gases 17 percent below 2005 levels by 2020.

To win over Republicans and pro-drilling Democrats such as Sen. Mary Landrieu of Louisiana, the bill calls for expansion of offshore drilling, which some Democrats have said they now oppose because of the Gulf spill.

"Some believe the oil spill has enhanced the chances energy legislation will succeed. I do not share their view," Graham said.

He said he still thinks that offshore drilling is needed for the country to become energy independent. "When it comes to getting 60 votes for legislation that includes additional oil and gas drilling with revenue sharing, the climb has gotten steeper because of the oil spill," the senator said.

He said it makes sense to find out what happened in the Gulf spill, take steps to prevent future accidents and build a consensus for expanded offshore drilling.