The US presidents have no legal control over the Conggress; however there are political and practical ways the president can exert influence over Congress. Sometimes,but certainly not always, the majority of the houses of Congress are of the same political party as the president and those members will sometimes go along with what that president wants them to do.
second continental congress
parliament
because we should
Voters choose the people who represent them and if they don't like the elected person they can vote him or her out.
Washington
The President . . .Added: . . . with the approval of Congress
Political Convention
If we are talking politics or party affiliation, it means as an alternative to being a Democrat or a Republican or with some other political party, you choose to register to vote as a person not affiliated with a specific political party.
Political parties choose their leader by democratic means.
Congress
The president can either choose to sign the bill into law or veto it, but Congress can override a veto.