Federal Railroad Administrator Robert W. Blanchette, the last member of former Transportation secretary Drew Lewis' innermost circle still at the department, resigned yesterday effective May 1.

Blanchette, a Democrat Lewis recruited because of his railroad experience, said he will return to private law practice here and will serve as chief executive officer of TGV-US, a firm that will promote the French high-speed passenger rail system in the United States.

The only serious high-speed rail plan under way here is a line in California. Backers of that system are said to be committed to Japanese technology. Asked yesterday if that were the case, Blanchette said, "I don't know; we'll find out. I'm still on government time."

Blanchette said he was not pushed out the door by Secretary Elizabeth Hanford Dole. "I had originally set two years as a target date, and I have gone a little beyond two years," he said.

Blanchette has overseen the passage of legislation that could reduce the federal role in railroading. Conrail, the Northeastern federal railroad, "has been made profitable and will be denationalized," Blanchette said. "Amtrak has been given new management and direction; its subsidies are declining, and it has been put on a business basis . . . We are now authorized to convey the Alaska Railroad from federal hands to the state."