WASHINGTON - Republicans drew on the support of independents and the energy of tea party activists to fashion a resounding victory in the House in midterm elections, increased their strength in the Senate, and quickly served notice they intend to challenge President Barack Obama with a conservative approach to the economy.

"We hope President Obama will now respect the will of the people, change course, and to commit to making changes they are demanding," Ohio Rep. John Boehner, the House speaker-in-waiting, told cheering partisans as GOP gains mounted Tuesday night.

Obama called Boehner to offer congratulations, and also telephoned Senate Republican leader Mitch McConnell and top Democrats in a series of conversations that reflected the shifting balance of power...