Published: May 16, 2012 4:46 AM EDT

FORT MYERS, Fla. - Senator Bill Nelson wants a new political attack ad taken off the airwaves in Florida.

In a letter from his attorneys, the Senator's office says the new ad paid for by the U.S. Chamber of Commerce includes incorrect statements about the impact of President Obama's health care law.

"Did Bill Nelson consider the consequences when he cast the deciding vote for Obamacare?" the ad asked.

The commercial started airing on Florida TV stations last week. The advertisement claims Sen. Nelson's support of the health care law would be especially damaging to seniors and Medicare.

"Obamacare will be nightmare for Florida seniors," the USCC ad said.

The senator's lawyers sent letters to television stations across Florida, asking them to stop airing the ad, pointing to findings by political watchdog websites like Factcheck.org and Politifact, which questioned the ad's accuracy.

"20 million people could lose their current coverage," the ad claims, but it doesn't tell the whole story. The ad cites a Congressional Budget Office report, which found 20 million people would not have employer-funded insurance. However, that was the worst case of four scenarios.

The CBO says its most likely a much smaller number-- 3 to 5 million wouldn't have employer-paid coverage.

"But Senator, seniors will see $500 billion in cuts to fund Obamacare," the ad claims.

This is the claim the Senator's office disagrees with most. The Congressional Budget Office says medicare spending would actually increase by about $900 billion dollars in the next ten years.

The CBO says the $500 billion mentioned in the ad is part of cost savings through changes in payments to hospitals, and higher premiums for wealthier seniors.

The ad continues to be seen over Florida airwaves. Station managers say television stations cannot control the content of paid political ads. Opposing groups are given the same opportunity to buy airtime to broadcast their own claims. Any disputes about the truthfulness of a political ad would be between the opposing sides; not the TV or radio stations airing the commercials.