Midterms to test Trump's value as endorser, ally for GOP candidates

President Donald Trumps gestures during a roundtable discussion on tax reform at Cleveland Public Auditorium and Conference Center in Cleveland, Ohio, Saturday, May 5, 2018. (AP Photo/Manuel Balce Ceneta)

President Donald Trump’s approval rating is gradually climbing toward levels it has not reached since last spring, and along with it, Republican prospects for retaining control of Congress in November are rising, but doubts remain about the extent to which his presence on the campaign trail can offer an advantage for GOP candidates.

This has so far been a good week for Trump. Hours after welcoming three American hostages home from North Korea Thursday, the president announced his historic meeting with Kim Jong Un will be held in Singapore on June 12.

On Tuesday, Trump fulfilled a campaign promise by withdrawing the U.S. from the Iran nuclear deal, which he long maintained was the worst deal ever negotiated.