Jeremy Ben-Ami, founder and president of J Street, the liberal pro-Israel advocacy organization that hosted Mr. Baker at its convention in Washington this week, said the Republican Party had grown more radical, leaving behind the former secretary of state and others like Brent Scowcroft, who was national security adviser under the first President George Bush, and Colin L. Powell, another former secretary of state.

“These used to be the center of the Republican Party,” Mr. Ben-Ami said. “I don’t think they’ve shifted. They’re still saying the same thing. The Republican Party of today has moved so far to the right they can’t relate to what these folks are saying.”

In his speech on Monday night, Mr. Baker said he had “been disappointed with the lack of progress toward a lasting peace” between Israelis and Palestinians and recalled that Mr. Netanyahu had once spoken out in favor of a Palestinian state as part of an eventual solution.