The standoff between Congress at the executive branch over a secret CIA assassination program is heating up.

Sen. Russ Feingold (D-Wis.) is challenging Director of National Intelligence Dennis Blair's assertion that the program was legal. This follows an announcement on Friday by Rep. Silvestre Reyes (D-Tex.) that the House Intelligence Committee would investigate whether the CIA acted illegally by keeping Congress in the dark about the program.

In a letter to Blair, obtained by Greg Sargent, Feingold calls out the intelligence chief's comments in a Washington Post story, in which he claimed the program was within the bounds of the law.

Feingold is now challenging Blair to get DNI lawyers to back up that claim:
According to a story on Thursday in the Washington Post, you stated that the failure to notify the congressional intelligence committees about a program recently cancelled by CIA Director Leon Panetta did not violate the law. I disagree and believe that the program in question fit squarely within the notification requirements of the National Security Act. I therefore request that you provide me with your analysis, and any analysis by the DNI General Counsel, supporting your conclusion.

Feingold sits on the Senate Intelligence Committee, raising the prospect that panels in both chambers will now bring pressure against the intelligence agencies.