From Gallop here: http://www.gallup.com/poll/1645/guns.aspx
92% percent of Americans polled thought that gun control laws should stay the same (34%) or be more strict (58%).
From Fox News here: http://www.policymic.com/articles/22816/40-percent-of-guns-are-sold-without-background-checks-because-of-people-like-larry-pratt
40% of the sales there is no such screen on the person buying the gun.
Just be because you don't agree with it, don't assume it's not accurate. Unless you have some other info.
Your links do not support the accuracy of the 40% and 90%.
Obama and Co. tout the 90% support UBC but even in the link you showed, only 58% favored more strict gun laws. While 34% supported keeping current laws and 6% for less laws. Also of note, favoring more strict gun laws is very vague and it is disingenuous to apply that vague poll question to the specific nature of UBCs. Even then you could only say the 58% support UBC.
The 40% of guns sold without checks is a flat out lie. Truth is we don't know. Here is a run down of the history of the 40% myth. http://www.nationalreview.com/articles/338735/40-percent-myth-john-lott
So yes, I believe it can be assumed these numbers are fraudulent. Just because they want to push gun control, doesn't mean they should be able to just make **** up or twisted polling results beyond recognition.