Known for navigating the state Capitol’s backrooms and this city’s complicated political landscape, state Sen. Leland Yee now is accused of consorting with notorious felons, accepting money for his cash-strapped political campaigns in exchange for favors and promising undercover FBI agents he could deliver connections to international gun runners.

In a stunning development that almost certainly torpedoes Yee’s quest for statewide office, the San Francisco Democrat wound up glum and disoriented in a federal courtroom Wednesday. The politician who introduced anti-gun-violence legislation is now charged with trafficking in firearms and public corruption in an FBI undercover operation that could land him in prison for years.

Democratic leaders in Sacramento, already stung by another recent federal corruption case, exhorted Yee to immediately step down. Senate President Pro Tem Darrell Steinberg, D-Sacramento, called the allegations against Yee “shocking” and “surreal.”