(CNN) – Whatever goodwill Sen. Joe Lieberman may have still had with Democrats may be gone after his criticism of Sen. Barack Obama in an address to the Republican convention Tuesday.
"It's a little bit sad," New Mexico Gov. Bill Richardson told CNN Wednesday. "I think he must be very bitter after his Senate issues with Democrats and the fact that he wasn't supported in the primaries but this is just going too far."
The Democrat-turned-independent's split from his former party has centered largely on issues of foreign policy - especially the conduct of the Iraq war, where Lieberman agrees with the views of his friend Sen. John McCain, the presumptive Republican nominee.
"I don't believe that Sen. Lieberman still has credibility among Democrats," Richardson told Kiran Chetry on American Morning. "He's basically said that anybody, like myself and many others, that have opposed this war - that want to bring our troops home safely but as quickly as possible - are basically not just wrong, but unpatriotic."
Richardson also took the opportunity to take a swipe at Alaska Gov. Sarah Palin, the presumptive Republican VP nominee. "Foreign policy, national security experience is something that she obviously doesn't have," said Richardson, who served as the U.S. Ambassador to the U.N. under President Bill Clinton. "To have a vice president without those credentials is going to be a problem."