Party leaders of the United States House of Representatives
Traditionally, the Speaker is reckoned as the leader of the majority party in the House, with the Majority Leader as second-in-command. For instance, when the Republicans gained the majority in the House after the 2010 elections, Eric Cantor succeeded Boehner as Majority Leader. Despite this, Cantor and his successor, Kevin McCarthy, have been reckoned as the second-ranking Republicans in the House, since Boehner is still reckoned as the leader of the House Republicans. However, there have been some exceptions. The most recent exception to this rule came when Majority Leader Tom DeLay generally overshadowed Speaker Dennis Hastert from 2003 to 2006. In contrast, the Minority Leader is the undisputed leader of the minority party.

Q: What is the title of seconde in command for majority party in congress?
Majority Leader