Two of the biggest backers of the effort to suspend the state's landmark climate change law contributed $1.5 million last week to the rollback initiative.

But with about a week to go before the election, the Proposition 23 campaign appears to be losing the fundraising battle by a 3-to-1 ratio.

On Friday, San Antonio-based refiner Valero Energy Corp. contributed $1 million to the Yes on 23 campaign, bringing its total contributions to the controversial ballot initiative to nearly $5.1 million, according to filings with the California secretary of state's office.

Tesoro Corp., another San Antonio-based refiner, chipped in $500,000 on Friday, bring its total to $2 million.

So far, the Yes on 23 campaign has raised $10.6 million.

But the No on 23 campaign has raised more than $31 million, including $700,000 from Microsoft Corp. co-founder Bill Gates, $1 million from Academy Award-winning filmmaker James Cameron and $1 million from venture capital guru Vinod Khosla.

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