WASHINGTON  Representative John A. Boehner of Ohio is set to complete a remarkable political revival Wednesday when he becomes the 61st speaker of the House, placing him squarely at the crossroads between the desires of conservative activists to reshape Washington and the reality of delivering in a divided capital.

Driven from his party’s leadership in 1998 and sidelined for nearly a decade, Mr. Boehner, a 61-year-old Ohio native who revels in his big-family, Roman Catholic roots, now faces the challenge of harnessing the Tea Party zeal that propelled him to power without disheartening those who might be expecting too much.

While he will preside over a substantial and energized Republican majority, Mr. Boehner must contend with a Democratic president with whom he has little personal history and a Democratic Senate leader who is disinclined to make Mr. Boehner’s life easier and who failed to consider hundreds of bills passed by the House even when his own party ran it.

“The problem is going to be the grass-roots movement out in the countryside,” said Vin Weber, a former Republican House member and Washington lobbyist who served with Mr. Boehner in the 1990s. “They have no sense of the limits on a party that controls only one of the three seats of power. Managing that relationship is going to be difficult.”