The phrase "a questionable claim" is correct and usable in written English.
It can be used when discussing a statement or assertion that lacks credibility or is open to doubt.
Example: "The scientist presented a questionable claim about the effectiveness of the new drug without sufficient evidence to support it."
Alternatives: "a dubious assertion" or "a suspect statement".
In Syria and Iraq, according to the president, America is "stopping ISIL's advance"—a questionable claim.
(A questionable claim: actors respond to the camera as if it is looking at them).
I'm president, largely because I'm the only one sober enough to make a speech at the presentation dinner, although that was a questionable claim this year.
Mr. de Blasio was sharply criticized over a questionable claim in his previous ad that he was the "only" candidate who would reform the city's policing tactics.
His diary, which gives a useful account of the war, contains a questionable claim that he played a crucial role in the Swedish victory.
According to the article, information for the ratings is gathered by D. H. Doelker "on visits to East Africa, by comparing what the brochures say and by studying clients' responses to questionnaires after tours". This is a questionable claim.
But he thought it "unlikely to find favour with those Labour MPs who support Trident's renewal on the grounds that Britain needs a nuclear arsenal to maintain its status in the world" which is itself "a very questionable claim".
It also makes a more questionable claim – that improvements are being made in the way offenders' needs are met: many more are allowed to work and stay closer to their homes.
Says the Brookings Institute's Gary Burtless, "They're going to be way in the back of the line with a very questionable claim, compared to some of the more legitimate ones Andersen is facing right now".
Right after he was confirmed, EPA Administrator Scott Pruitt said he would achieve cleaner air through "cooperation between the States and EPA". It was always a highly questionable claim, since Pruitt's record of 14 lawsuits against clean air and water rules and lax record in Oklahoma suggested he really just wanted to allow companies to pollute without legal consequence.
President Trump declared Wednesdayon Twitter that there was "no longer a Nuclear Threat from North Korea," a bold and questionable claim following his summit with leader Kim Jong Un that produced few guarantees on how and when Pyongyang would disarm.
