WASHINGTON – President Barack Obama marked the 100th day of his presidency Wednesday with a rosy assessment of the start of his administration, asserting that his policies would “lay a new foundation for growth” and sounding a note of hope for beleaguered American automakers.

In a prime-time news conference, Obama said he was “very hopeful, more hopeful than I was 30 days ago” that Chrysler would avoid bankruptcy and remain “viable” through a merger with the Italian automaker, Fiat.

Obama seized the widely watched 100th-day milestone in office to promote the image of an activist president who has made early progress in the face of an economic crisis and remains determined to press on with an ambitious agenda.

“We are off to a good start. But it is just a start,” Obama said. “I am proud of what we have achieved, but I am not content. I am pleased with our progress, but I am not satisfied.”

The news conference was scheduled for a prime-time audience, offering maximum exposure to tens of millions of Americans, and followed a presidential trip earlier in the day to the electoral battleground state of Missouri for a town meeting marking his 100th day in office. Senior presidential advisers also fanned out during the day for network television interviews, helping to frame media coverage.

Though Obama officials had derided the 100-day mark, derived from the flurry of activity at the start of Franklin Roosevelt’s administration, as a meaningless “Hallmark holiday,” his administration has been far more aggressive in promoting the occasion than his immediate predecessors.

President Bill Clinton spent the day on photo opportunities with the king of Spain and a group of Lubavitcher rabbis, and President George W. Bush marked it a day late with a White House luncheon for members of Congress.

As Obama marked his 100th day, Congress passed his administration’s ambitious budget, which offers a blueprint for broad health care transformation, expanded aid to education and action to combat global climate change. Language in the budget eases the prospects for Obama’s health care agenda with provisions to prevent a filibuster so he will not need to gain a 60-vote super-majority in the Senate.

He also welcomed into the Democratic Party a defecting Republican senator, Arlen Specter of Pennsylvania, at a White House ceremony in the morning, furthering the portrait of an opposition in disarray.

Polls indicate public confidence soaring. An ABC News poll conducted just before Obama’s 100-day mark found that, despite the recession, the share of pollees who said the country is moving in the right direction had risen to 50 percent – the highest level in six years and a stunning climb from the 19 percent who said so on the eve of his inauguration.

That surge in optimism came despite gross domestic product estimates released Wednesday that showed the economy contracting at an annual rate of more than 6 percent for two quarters in a row – the first time the U.S. economy has performed so poorly over a six-month period in more than 50 years.

Speaking at a town-hall styled meeting in the St. Louis suburb of Arnold, Mo., Obama said that, despite the hard times, the country is making progress.

“We have begun to pick ourselves up and dust ourselves off, and we’ve begun the work of remaking America,” Obama said, stirring cheers at the campaign-like event.

Obama noted a list of economic and other problems, “challenges of unprecedented size and scope” which he said were waiting for him when he took office.

Obama appealed for patience from Americans suffering from the economic recession – and sought support for his solutions.

“I know you’ve heard, ‘Oh, Obama’s spending all this money … blah, blah, blah,”‘ he said. “I am happy to have a serious conversation about how we are going to cut our health care costs down over the long term, how we are going to stabilize Social Security. … We are going to have to tighten our belts, but we are going to have to do it intelligently.”