WASHINGTON - President Barack Obama delivered a dire sales pitch for his massive economic stimulus package Monday night, facing millions of Americans for the first time since his inauguration to warn of a looming catastrophe if the bill doesn't swiftly become law.

"The plan is not perfect," a stern, forceful Obama said in the opening statement at his first prime-time, televised news conference, held in the stately East Room of the White House.

"No plan is. I can't tell you for sure that everything in this plan will work exactly as we hope, but I can tell you with complete confidence that a failure to act will only deepen this crisis as well as the pain felt by millions of Americans."

While his prepared remarks focused on the foundering economy, they were followed by questions from the White House press corps on a variety of issues, including Iran and Afghanistan.

Millions of Americans were expected to tune in, but Obama had a tough sell on his hands. Recent polls suggest almost half of Americans don't like the US$827 billion bill, believing it's too fat with unnecessary spending, even as Obama's personal approval ratings remain sky-high.

The president opted to hold his first formal, televised White House news conference far earlier than many previous presidents. While John F. Kennedy held one just 10 days after his inauguration, most have waited months, including George W. Bush and Bill Clinton.

After weeks spent trying to reach out to Republicans to gain support for the bill - including wining and dining them at White House soirees - Obama repeatedly criticized them Monday for suggesting the package is full of wasteful spending.

"When I hear that from folks who presided over a doubling of the national debt, then, you know, I just want them to not engage in some revisionist history," he said.

"I inherited the deficit that we have right now and the economic crisis that we have right now."

A feisty Obama also scoffed at suggestions from Republicans that he came to the White House keen to burn through mammoth amounts of money.

"I would love not to have to spend money right now," he said. "This notion that somehow I came in here just ginned up to spend $800 billion, you know, I mean, that wasn't how I envisioned my presidency beginning. But we have to adapt to existing circumstances."

Obama also ventured deep into foreign-policy territory, saying his administration hoped to engage Iran in the coming months, but acknowledging it would be a challenge after years of mutual mistrust.

He said there's "no doubt" there are safe havens along Pakistan's border with Afghanistan where terrorists are operating, adding the U.S. will work to convince Pakistan it faces as much danger from their presence as does America.

Neither al-Qaida nor Osama bin Laden would be allowed to operate "with impunity" from safe havens in Afghanistan, Obama said as he acknowledged the Afghan front in the ongoing conflict would likely prove even tougher than Iraq.

"We are going to need more effective co-ordination of our military efforts with diplomatic efforts, with development efforts, with more effective co-ordination with our allies in order to be successful," he said.

"My bottom line is that we cannot allow al-Qaida to operate, we can not have those safe havens in that region, and we're going to have to work both smartly and effectively, but with consistency, in order to make sure those safe havens don't exist."

Obama also made mention of the deaths Monday of four American soldiers in Iraq as he promised to review a long-standing George W. Bush policy of blocking media coverage of repatriation ceremonies in the U.S., when the remains of slain American servicemen are returned home.

Earlier in the say, Obama travelled beyond D.C.'s corridors of power to take his bleak sales pitch to the American people, visiting a heartland town decimated by the deepening recession to push for swift passage of the stimulus bill.

Obama took a road trip to Indiana and spoke directly to America's economic casualties during a town-hall meeting in Elkhart, a city of just over 50,000 people where the jobless rate is twice the national average.

"We can't afford to wait," Obama said. "We can't wait to see and hope for the best. We can't posture and bicker and resort to the same failed ideas that got us in into this mess in the first place."

The Senate is expected to pass the stimulus bill on Tuesday after voting late Monday to end debate on the package. But after its Senate passage, the stimulus package will have to be reconciled with the House's version of the bill - meaning another few days of ferocious skirmishes between Democrats and Republicans.

Obama hopes to have the bill on his desk on Feb. 16 - President's Day in the United States - to sign into law. That means Congress will be working under a punishing deadline in the days to come.

Like he did in Elkhart hours earlier, the president warned again on Monday night that a failure to act quickly by Congress "could turn a crisis into a catastrophe."

The president is travelling to Fort Myers, Fla., on Tuesday, another region of the country hit hard by the recession, in Day 2 of his attempt to reach out to Americans and build public support for the bill.

Befitting the grim economic times, the packed news conference was a largely sober affair, featuring only a couple of light-hearted moments.

One came when the president was asked a question about his vice-president, Joe Biden.

"If we do everything right, if we do it with absolute certainty, we stand up there and we make really tough decisions, there's still a 30 per cent chance we're going to get it wrong," Biden said last week.

Before the reporter had even finished reciting Biden's remarks, noting that the vice-president had said they were based on private conversations with his boss, Obama burst out laughing.

"I don't remember exactly what Joe was referring to, not surprisingly," Obama said.

And after weeks of devastating economic news, the president wrapped up his one-hour news conference on a positive note, saying he was convinced the stimulus package would succeed in pulling the American economy from the brink of a depression.

"I am an eternal optimist," Obama said before striding out of the East Room.

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