Republicans' legislative struggles may also be weighing on Trump's popularity.
Twice as many of those surveyed preferred the Obamacare health programme as those who favoured Republican plans to replace it.
The US Senate will "defer" its work on repealing Obamacare for a week as senior lawmaker John McCain recovers from blood-clot surgery, the chamber's Republican leader, Mitch McConnell, said Saturday.
The repeal effort is opposed by all Democrats, and the loss of a single Republican vote could doom it.
Trump had seemed to revel in his brief Parisian respite from all the talk of Russia and health care.
He and President Emmanuel Macron reviewed a pomp-filled Bastille Day military parade and dined in a posh restaurant on the Eiffel Tower.
The US president then spent two days playing maitre d' to professional female golfers taking part in a tournament at his Bedminster course in New Jersey, waving to cheering onlookers in his signature red "Make America Great Again" hat.
Trump flew back to Washington on Sunday evening — without Melania, who the White House said was spending some time with their young son Barron.
The president's return brings him straight back into the intensifying storm over his campaign's contacts with Russia.
Even some erstwhile supporters seem to be troubled by the Russia contacts of Trump's son and advisers, and by the administration's shifting explanations.
Shepard Smith, an anchor on Fox News, a network that has often been in lockstep with the Trump White House, accused the administration of "mind-boggling deception."
"If there's nothing there, and that's what they tell us, why all these lies?" he added.
And key Democrats, like Mark Warner, vice chair of the Senate Intelligence Committee investigating Russian meddling, have expressed deep scepticism over administration attempts to gloss over the Trump Jr. meeting.
News of the meeting was "very troubling," said Warner. "Clearly, this administration has not been forthcoming."
He told CBS's "Face the Nation" he wanted to hear from everyone who attended the meeting — which would include Trump son-in-law Jared Kushner and former campaign head Paul Manafort — adding that the recent revelation "obviously moves our whole investigation to another level."