Washington (CNN) -- Republicans led by presidential challenger Mitt Romney served up a heaping helping of political red meat on Friday, launching a salvo of attacks on President Barack Obama that called him a liar and a failed leader. Romney told an interview broadcast on ABC that his biggest concern about the three upcoming presidential debates is that Obama will be untruthful. "The president tends to, how shall I say it, to say things that aren't true," Romney said, contemplating whether he would spend debate time "correcting things that aren't quite accurate" or "talking about the things I want to talk about."
@highlight
NEW: "These are difficult days," President Obama says of anti-American unrest
@highlight
Mitt Romney says Obama will be untruthful in the debates
@highlight
Paul Ryan blames Obama for anti-American unrest in Arab nations
@highlight
The Obama campaign calls Ryan's criticism "over-the-top" and dishonest
In an already nasty and bitter campaign, @placeholder's pre-emptive strike less than three weeks before the first debate on Oct. 3 signaled more personal attacks to come as the election campaign gallops toward the November vote.