Some members of the California delegation of the U.S. House of Representatives have warned regulators not to block a controversial advertising agreement between Google. and Yahoo.

In a letter sent to the U.S. Department of Justice Friday, the California representatives wrote of their concern that any effort by the Justice Department to block the deal “could detrimentally affect the online advertising market and electronic commerce.”

“If the DOJ blocks this agreement we fear that the threat of additional scrutiny may chill future agreements,” read the letter, which characterized such advertising partnerships as “standard among Internet companies.” The letter was signed by 11 of the 53 California members of the U.S. House of Representatives.

Last week, 10 members of the U.S. House of Representatives Committee on the Judiciary sent a letter to the Justice Department, expressing concern about the agreement and urging a careful review.

The Justice Department is continuing to review the agreement and is expected to indicate whether it will seek to block the deal by early October. Google and Yahoo, which voluntarily delayed implementing the deal, are already preparing to start implementing it in the coming weeks.

Yahoo has launched a site, help.yahoo.com/searchagreement, laying out why it thinks the deal ought to be allowed. Yahoo argues that the deal will make it a stronger competitor in the online advertising industry, not a weaker one.