1. Congress Majority
Here is the current numbers associated with each party in both houses of Congress.

3. House of Representatives (435)
Republicans (234) 54%
Democrats (201) 46%
Independent (0)
Vacant (0)
Republicans control the House having a majority.

4. Senate (100) Republicans (53) 53% Democrats (45) 45%
Independent (2) 2%
Vacant (0)
Republicans control the Senate having a majority

5. Speaker of the House
He is the presiding officer of the House of Representatives and is elected by the members of the House.
He is the 2nd man in succession after the Vice President and before the Senate Pro Tempore.
The current Speaker of the House is Paul Ryan of Wisconsin.
He is Republican since the Republican control the House.

6. Senate Pro Tempore
He is the presiding officer of the Senate (when the Vice President is not available) and is elected by the members of the Senate.
He is the 3rd man in succession after the Speaker of the House and before the Secretary of State (cabinet member).
The current Senate Pro Temp is Orrin Hatch of Utah.
He is Republican since the Republicans control the Senate.

7. Majority and Minority Leaders
Each party within each house select a Majority and Minority leader to lead and represent their party. Each Majority and Minority leader have a whip under them.
House *
Senate
Kevin McCarty (R)
California
Nancy Pelosi (D)
California
Mitch McConnell (R)
Kentucky
Harry Reid (D)
Nevada

8. Whips
Majority Whips
Steve Scalise
Minority Whip
Steny Hoyer
Official of a political party whose task is to ensure party discipline in a legislature. Whips are the party's "enforcers", they invite their MPs to attend votings and to vote according to the official party policy.