Updated from 2:26 p.m. EDT

General Motors ( GM) said sales declined 45% in March, but picked up at the end of the month.

March 31 was "our best final day since going back to September," said Mark LaNeve, GM's top sales executive, on a sales conference call. "We had a strong close."

Not only do sales normally pick up in the last day of the month, and particularly in the last day of the quarter, due to dealer incentive programs, but March 30 was the day that President Barack Obama revealed his plan for the federal government to save GM and back its warranties if necessary.

"He gave the whole industry a lift," said Mark DiGiovanni, executive director of global sales analysis. "All of a sudden everybody was up, across all six OEMS (original equipment manufacturers). It may have (also) been Obama's assurance he was backing us and Chrysler."

On a conference call, Ford ( F) executives also said that sales picked up in the last six days of March.

GM said it delivered 156,380 vehicles in March. Its sales were up 23% over February, compared with an average month-to-month gain of 21% over the past five years.

Added DiGiovanni: "The seasonally adjusted annual rate for March will come in about 10 million units, a significant increase over what we thought the industry would come in at."

"We feel the industry is starting to show that we've reached hopefully the bottom," he said.