More companies from across the corporate spectrum are joining a long-shot advocacy effort to pass a carbon tax in a bitterly divided Congress.

Driving the news: General Motors, Ford, IBM and two electricity companies — Calpine Corporation and Vistra Energy — are putting money toward a lobbying campaign that would put a price on CO2 emissions and refund revenue back to consumers.

Where it stands: These companies join several others funding Americans For Carbon Dividends (AFCD), the lobbying arm of the Climate Leadership Council (CLC), which is a coalition of strange bedfellows that includes companies, environmental groups and former Republican lawmakers.

The groups’ proposal would impose a $40-a-ton tax on CO2 emissions and cut U.S. carbon emissions in half by 2035.

Ted Halstead, CEO of the CLC, says the goal is to have both chambers of Congress introduce bipartisan measures sometime next year. He had previously pushed for it to get done by the end of this year, but he now says the effort has been delayed by the impeachment saga.

By the numbers:

General Motors, Ford and IBM each gave $100,000 to the campaign this year, while Vistra is giving $1 million over two years. Calpine is giving an undisclosed amount, according to Halstead.

These companies join ConocoPhillips, Exxon, Exelon and several renewable energy companies in funding the campaign.

AFCD raised more than $5 million this year and aims to raise “considerably more” next year, Halstead says.

But, but, but: These figures are often quite small compared to the companies’ overall lobbying efforts. For example, General Motors has spent more than $6 million in the first three quarters of this year; Ford, more than $3 million.

The intrigue: GM and Ford are agreeing here, but they’re on opposite sides of a brewing fight between the Trump administration and California over federal and state-level efforts on fuel-efficiency standards.

Reality check: Although Republicans are increasingly acknowledging climate change is a problem, few are on board with sweeping new policy — which this would be. Meanwhile, the most vocal Democrats say a carbon price by itself isn’t nearly enough to combat climate change.

Go deeper: Carbon tax campaign unveils new details and backers