Sen. Al Franken took an offensive stance during a hearing this afternoon on the proposed merger between NBC and Comcast, repeating that the companies cannot be trusted and accusing Comcast's CEO of contradicting his own legal team.

Franken, a former NBC employee who still receives residual checks from the network, was the most heated lawmaker in the room as he grilled the two companies' execs. In his opening statement, Franken said he didn't trust their promises regarding the merger.

"While I commend NBCU and Comcast for making voluntary commitments as part of this merger, you'll have to excuse me if I don't trust these promises," Franken said. "And that's from experience in this business."

The primary worry among lawmakers is that a merger may incentivize Comcast to raise the price of NBC content -- to the detriment of rival providers and consumers. Company heads have pledged this will not happen, saying it is in their interest for content to be widely distributed.

Franken countered that price increases do not necessarily mean rival cable companies would stop buying the content.

"If a cable company wants to carry Saturday Night Live and they can't, no one's going to use that cable company," Franken said. "They have to get NBC. It would be death to any cable company. So maybe you're not going to charge them 10 times as much but you can charge them twice as much."

During questioning, the Democratic senator accused Comcast CEO Brian Roberts of misleading him a week ago when the cable chief said in a private discussion that program carriage rules would protect consumers. Franken said he later discovered that Comcast's lawyers argued in 2008 that the rules are largely unenforceable.

"In other words, looking to get approval for this merger, you sat there in my office and told me to my face that these rules would protect consumers," Franken said. "But your lawyers had just finished arguing in front of the commission that it would be unconstitutional to apply these rules."

Roberts responded that there may have been some confusion about which rules they were talking about during their discussion.

Franken then asked NBC CEO Jeff Zucker to admit that the company had broken promises in the 1990s regarding ownership rules. Zucker largely dodged the question, saying it was a long time ago and there may have been other factors at play.

Commenting that a private meeting should be convened of interested lawmakers and the execs, Sen. Arlen Specter added a bit of levity to the situation as he noted the complexity of Franken's questions.

"[Franken] is in a lot different position having been an entertainer on the TV shows," Specter said. "The best Sen. Kohl and I do is CSPAN 2. So we're not in Sen. Franken's league."

Here's Franken's opening statement:

and here's when things started to heat up: