For two years, Tea Party lawmakers in the House have been the stubborn barbarians at the gate, strong-arming their often reluctant Republican colleagues by refusing to compromise on spending, taxes, debt or social policy.

But Paul Ryan’s ascendency to No. 2 spot on the Republican ticket is a signal event for a movement that counts him as one of their own. If Mitt Romneywins in November, a Tea Party favorite will be a heartbeat from the Oval Office.

More than that, Mr. Ryan is now unquestionably the face of the Tea Party caucus in Washington, and his success is certain to embolden House lawmakers whose proudly unyielding approach to governance has contributed to legislative gridlock.

Once considered a fringe of the conservative coalition, Tea Party lawmakers are now indisputably at the core of the modern Republican Party.

“Gov. Romney’s selection of Congressman Paul Ryan is an excellent choice and a game changer for the presidential election,” Representative Kevin Brady of Texas said in a statement. “It’s now a campaign of ideas on how best to get this economy moving again, balance the budget and restore America.”

He added: “My guess is that Barack Obama has a sick feeling in his stomach today.”