The letter, which calls for “legal status” for the 11 million immigrants here illegally, begins with a simple appeal: “We write to urge you to take action to fix our broken immigration system.”

The effort was organized by Carlos Gutierrez, who was secretary of commerce under President George W. Bush and was a founder of a “super PAC,” Republicans for Immigration Reform. The letter is the beginning of a campaign to lobby Republican lawmakers in favor of a broad immigration bill as they return to their districts for the August break…

A cross-section of Republican donors and fund-raisers signed the letter. They include Karl Rove, a deputy chief of staff in Mr. Bush’s White House; former Vice President Dan Quayle; Tom Stemberg, a founder of Staples; and Frank VanderSloot, the founder of Melaleuca Inc.