A solid U.S. economic recovery might soon enable the Federal Reserve to drop its promise to keep interest rates low for an "extended period," Richmond Fed President Jeffrey Lacker said on Monday.

In a wide-ranging interview in his Richmond office, Lacker told Reuters that Europe's debt troubles, which have sparked worries about a renewed credit crunch, had not materially affected his outlook for U.S. growth.

"The expansion is on track," Lacker said.

"Consumer spending continues to expand at a reasonably strong pace given the circumstances. We continue to see strength in business spending on equipment and software. Those are going to bring the economy forward."

Asked if conditions were robust enough to allow the Fed to alter its repeated commitment to keep borrowing costs at exceptionally low levels for an "extended period," Lacker said: "Not now. Maybe soon."