the justice league lost to the avengers because the avengers were more powerful
the senate house
Their parties have more members in it
the lieutant governor
Neither house is more powerful than the other in a bicameral system. In the US, the House of Representatives and Senate make up the bicameral legislature.
the president of the senate is not a member of the majority party
Depends on what you mean by Congress. Technically, the Senate is one chamber of Congress and the House of Representatives is the other. Some people, though, refer to the House as Congress and the Senate as the Senate. If in asking this question you are meaning 'Is the House more powerful than the Senate' the answer is no. The Senate is more powerful than the House due to its powers of advise and consent over treaties and presidential nominations for the judiciary and executive branches.
senate majority leader
The House of Representatives has 435 elected members
In general, yes, this is one of the most powerful posts in Congress. However, the majority leader of the Senate is quite powerful as well--and in some ways is more powerful. For instance, the speaker of the House has to be reelected every two years, whereas the Senate majority leader is reelected only every six years has more control over judicial and other presidential appointment. Certainly both posts are powerful.
The floor leaders (aside from the Speaker of the House in the House of Representatives).
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The filibuster can be used in the Senate but not in the House