Question

Suppose the president wanted to start new programs to improve living conditions in big cities who would put the plan into action

Answer 1

Basically congress would make a bill and put into action aproved my other members of senate and house of representatives later, they would make whatever the states want put into action in all states and president signs it if the judicial branch does not declare it unconstitutional

Answer 2

The Department of Housing and Urban Development known as HUD.

HUD is one of the most influential government agencies. HUD is under the executive branch which means it usually carries out the orders of the President and his cabinet. Currently the HUD Secretary is Ben Carson who was appointed to his position by Donald Trump.