WASHINGTON — Republican presidential challenger Mitt Romney charged Wednesday that President Barack Obama is running a campaign "of enmity and jealousy and anger" and called on him to lift the tone of political discourse.

In an escalation of an increasingly acrimonious campaign, Romney went on national television to say he thinks Obama is "running just to hang onto power, and I think he would do anything in his power" to remain in office.

Asked if he was worried that people would think the presidential campaign has become "unhinged," the former Massachusetts governor replied, "I think unhinged would have to characterize what we've seen from the president's campaign."