At the same time there is a drawback to term limits on Senators.
Ted Kennedy was a big liberal proponent of Universal health care and was able to be that because of the legacy of the Kennedys. He was so popular, or was a special interest of other industries, that he was able to push for health care reform despite the industry.
Yet even if he was in the pocket of other corporations (he probably was, knowing how the senate operates), no one can speak ill of his importance. He was able to get a lot of great legislation through and that was largely because of his long tenure and ability to forge relationships. If he had been limited to one term, his ability to work as he did would be diminished due to the nature of the Senate.
So if not term limits, then just ban donations from citizens and corporations. Give everyone public funding of a certain amount.
But then there's a drawback to that too! The way you run a campaign can give signs to what kind of an executive you'll be. Take for example the brilliant campaign of Obama in '08 (even if you hate Obama you can't speak ill of how smooth his campaign worked for the most part despite the controversies with rev. wright, bill ayers, and the birth certificate). That gave signs to what kind of executive he'd be and for the most part, he's been a pretty solid Executive. He's had some controversies (Department of Agriculture firing Shirley Sherrod, him saying the cop was stupid to arrest gates, and sestak, and the DOJ being accused of some political bating), though they largely have been squashed and if they were a big deal, weren't really related to how he himself ran his administration some lower level problem or some comment the media took out of proportion (like saying they were stupid for arresting the guy. the guy was stupid for arresting him when he showed proof.) On top of that he's been able to get a lot done (despite how centrist the policies have been though for the most part they're pretty solid). So he's a pretty capable executive and that was demonstrated to how he ran his campaign (which colin powell said was almost military precision). The key problem for him may be communication and too close of a circle but that's largely emanuel's fault (though he did pick him, not that emanuel wasn't good at his job, he was outstanding), and the best communication can't calm a nation with 9.6% unemployment and in the middle of 2-3 wars.