Fun fact: Top politicians are flattered by attention from the president, which can only enhance an already strong sense of self-importance.

“He calls everybody all the time,” said Representative Tom Cole, Republican of Oklahoma.

Mr. Cole said he probably had more contact with Mr. Trump in 18 months than he did with Presidents Barack Obama and George W. Bush over their combined 16 years. “I have never seen a president who reaches out as consistently as this guy. It is just his style.”

Given his management approach — reserving ample television time with a phone close at hand — it is not surprising that Mr. Trump is known for spontaneously dialing up his supporters, and even the occasional Democrat.

He might also have more incentive to call because of his need to hold Republicans in line after his often incendiary remarks, as he did this month during a House effort to reprimand Mr. Trump for his demand that four progressive Democratic congresswomen “go back” to where they came from. Only four Republicans voted with the Democrats to condemn the president.

[Read more about President Trump’s attack on four congresswomen of color.]

Veteran Republicans say Mr. Trump employs the phone and the power of personality in a way that reminds them of Presidents Lyndon Johnson and Bill Clinton, both of whom were known for their success at influencing skittish members of Congress. Mr. Bush and Mr. Obama, in contrast, were considered distant figures by many of those on Capitol Hill; they might interact only at holiday receptions.