A second television advertising campaign pressing for action on climate change may have run afoul of legal requirements governing ads mentioning political candidates shortly before an election, according to campaign finance lawyers.

Last week, the Environmental Defense Action Fund launched a $4 million effort to press federal lawmakers to move aggressively against global warming as the Senate prepares to consider legislation to impose a so-called cap-and-trade system for carbon emissions.

“Some in big oil and coal will do anything to drive this bill into the ground,” a man says in one jarring spot as he is apparently driven into the earth by oil barrels being dropped from the sky.

About 25 versions of the ad running in various parts of the country mention one or two of more than three dozen senators and members of Congress. “Tell Speaker Pelosi we need a strong global warming bill now,” a narrator declares in one iteration of the spot.

In another ad that began airing yesterday, a talking candle that looks like a man melts as it offers reasons not to act. “Sure, climate change is a problem, but let’s not rush into anything. Let’s study it a while longer,” the candle-man says as his lips slide away. Graphics urge viewers to contact Ms. Pelosi or other lawmakers.

The legal difficulties arise because Ms. Pelosi is on the ballot in her district on Tuesday for a Democratic primary challenge to her congressional seat. Under the Bipartisan Campaign Reform Act of 2002, also known as McCain-Feingold after its Senate sponsors, expenditures for broadcast and cable ads mentioning a federal candidate in the 30 days before a primary must be reported to the Federal Election Commission. The names of donors who gave more than $1,000 for such ads also must be made public.

“It is covered by the electioneering communication provisions,” a Republican campaign finance lawyer in Washington, Jan Baran, said.

A spokesman for the Federal Election Commission, Robert Biersack, said the Action Fund, a lobbying group affiliated with the Environmental Defense Fund, had made no filings.

Asked about the absence of any report, a spokeswoman for the two groups, Emily Diamond-Falk, stressed that the ads were related solely to the pending legislation. “These ads have nothing to do with Speaker Pelosi’s primary election at all,” the spokeswoman said. “This is strictly about the Climate Security Act.”

Ms. Diamond-Falk said the campaign would cost about $4 million and was slated to run from May 23 to June 10. She said the ads were airing nationally and in Washington.

Earlier this month, The New York Sun reported that another group, the Alliance for Climate Protection, may have violated the law and disclosure requirements by running a television ad featuring Ms. Pelosi and a former speaker, Newt Gingrich. Lawyers said that ad was deemed a donation to her campaign because she participated in it.

“This is a little different,” Mr. Baran said of the new campaign. “It is permissible, but even a permissible ad would trigger a reporting obligation.”

The group might escape the obligation to file with the FEC if the costs for production and ad time for the spots mentioning Ms. Pelosi were below $10,000 or if the ads did not air in her district. However, versions of the ads posted on YouTube indicated that they were to play in San Francisco.

The electioneering rules were included in the McCain-Feingold law to address so-called sham issue ads which seemed to be primarily about tarring or boosting a candidate. However, a lawyer who works for the AFL-CIO and left-leaning nonprofit groups, Laurence Gold, said the rules may eventually be challenged in the Supreme Court because they place burdens on groups plainly not trying to influence any election.

“It’s an absurd requirement,” Mr. Gold said. “There are clearly going to be situations where people didn’t have any idea there was any requirement. In a way, it’s gratifying to me because it points out the overreach.”