The word “claims” is often used by journalists to indicate a statement made by a source that is either patently and provably false, or that cannot be verified by a journalist. While in some cases the statement cannot be verified because it is simply not something that can be proven, more often than not, the journalist is either too lazy or too strapped for time to investigate the veracity of the quote.
This word is a queue to the reader or viewer to do his or her homework and to take note of the fact that while a source made this statement, it may not in fact be true.
Saying that a source “claimed” something rather than using the much preferred and perfect word “said” also removed the news organization from any liability that they may face from printing or airing an outright lie. Essentially, most of what politicians have to say is a claim that either can’t be verified or can’t in any way be true.
Using the word “claimed” is the journalist’s way of winking at and nudging the audience that they should be taking this statement with an appropriately sized grain of salt.