Instead of meeting with House Democrats Thursday to argue in favor of passing a controversial climate change bill, former Vice President Al Gore has decided to meet one-on-one with them via phone calls.

House Speaker Nancy Pelosi said she had decided not to impose on the former vice president after the list of undecided lawmakers narrowed Wednesday. Gore had been scheduled to meet with Democrats on Capitol Hill at 1 p.m. ET. Thursday and was going to speak with the press at 2 p.m. ET.

"It was a question of what was energy efficient for the vice president," Pelosi said at her weekly news conference Thursday, explaining the absence. "We were narrowing the list of the undecided and thought perhaps another occasion we could call upon his time to come here."

Pelosi added that it was more energy efficient for Gore to continue coordinating efforts from Tennessee.

Senior Democratic sources told FOX News that in addition to the time commitment issue, they thought it was better if Gore worked the phones with targeted lawmakers. Gore is specifically reaching out to more liberal lawmakers who don't think the bill goes far enough, the sources said.

But speculation is swirling that Gore's presence would have been radioactive and could have caused more of a problem, a source told FOX News.

Senior Democratic leaders are pushing skeptical lawmakers to side with them to approve a measure that could have significant economic impact on the energy bills of many Americans and could even drive up the price of food by forcing utility companies to buy credits to pay for their carbon output.

Gore, who is well-known for his environmental views, has authored books on climate change an produced the Academy Award-winning documentary "An Inconvenient Truth" in 2005.