What Motive Does the President Have to Endorse Certain Candidates

What motive does the president have to endorse certain candidates within Congress?

A) Endorsing a candidate in Congress will give the president influence to demand support for a policy.
B) The president will endorse a candidate if he or she believes that candidate will make a good vice president.
C) The president may endorse a member of Congress to boost that member's chances of re-election.
D) Endorsing a candidate or member of Congress helps the president maintain a positive public image.