WASHINGTON (AP) — President Barack Obama said Saturday that the surge of immigrant children entering the U.S. illegally changed the politics surrounding the issue of immigration and led him to put off a pledge to use executive action that could shield millions of people from deportation.

Immigration reform advocates criticized Obama after White House officials said that the president would not act at summer’s end as he promised in June but would take up the matter after the midterm elections in November. In an interview taped for NBC’s “Meet the Press,” Obama rejected the charge that the delay was meant to protect Democratic candidates worried that his actions would hurt their prospects in tough Senate races.