Well, typically the winning candidate has the unified support of their party. So, if a Republican president wins, and Republicans control Congress, then the president basically has the support of Congress. It gets a little trickier when the opposing party controls Congress because then you have a divided government. Some people prefer a divided government because they believe the controlling opposition provides a check on the power of the president. Others are opposed to divided government because it makes executing the president's agenda more difficult, which is either good or bad depending on whether your party is in control of Congress.