He sounded at times like a senior executive making a PowerPoint presentation to middle managers and at others like a poet, but President Obama's underlying message to Congress on health care last night was simple:

Yes we can!

The president didn't actually use the iconic slogan from his 2008 campaign rallies. Rather, he argued that members of Congress from both parties agree on 80 percent of what needs to be done, from greater controls on health-insurance companies to reining in costs - despite the "partisan spectacle" of the summer.

"We did not come here to fear the future. We came here to shape it," he said. "I still believe we can act even when it's hard."

This morning, administration officials will be all over the airwaves. On Saturday, Obama returns to the campaign trail, literally, with a reform rally in Minneapolis.

The harder part will take place behind closed doors, as lawmakers on Capitol Hill put together a final bill. Already four of the five House and Senate committees with jurisdiction on the issue have moved competing proposals.

Obama will start by lobbying the centrist Democrats who hold the balance of power in the Senate. They are leery of a government-run, health-insurance program and worried about cost. But he will have to keep in the fold House liberals in his party who have embraced that "public option" as a cause.

The president's ultimate leverage: the midterm elections of 2010, when the Democrats have their congressional majorities on the line. They will want to have some kind of accomplishment when they face voters, who, according to the polls, widely believe the health-care system is broken.

Obama's goal was to reverse the tide of opposition to change that he helped create by letting the debate get away from him.

Hoping to avoid the my-way-or-the-highway approach with lawmakers that helped blow up President Bill Clinton's push for a health overhaul in the early 1990s, Obama has until this point deferred to Congress on the details. The president argued in principle for change but did not wind up driving the debate as it grew more heated over the summer.

Instead, conservative opponents of change took advantage of confusion on the issue - and the president's ambiguity - to accuse Obama and his Democratic allies of seeking a government takeover of health care. Some hurled debunked but persistent charges that the plan would ration health services or give free care to illegal immigrants.

Obama sought to swat down those "distortions" and "scare tactics" during the 48-minute speech and stressed that he was open to Republican ideas as the legislation is shaped. But he also served notice he would fight.

"Know this: I will not waste time with those who have made the calculation that it's better politics to kill this plan than improve it," he said.

But Obama reached out repeatedly to Republicans, many of whom have reasonable concerns about the impact an expansion of health-care coverage could have on the deficit.

The president even suggested that reform of malpractice laws should be included in the discussion. Republicans have always wanted to address what they consider the costly burden of lawsuits, but Democrats usually shy away from the subject because trial lawyers are major party fund-raisers.

Obama said he would order federal demonstration projects aimed at reducing malpractice suits but did not mention caps on jury awards.

He argued for the inclusion of a public health-insurance plan, which he said was the best way to put competitive pressure on private insurers to reduce costs and give coverage to Americans with no affordable options. But he said pointedly that he was "open to other ideas that accomplish our ultimate goal."

That statement was met with silence from the Democratic side of the aisle.

Most of the speech was given over to reassuring those who already have health-care insurance - about 85 percent of the population - that they would lose nothing by reform and would gain "stability and security" because insurers could no longer deny coverage for preexisting conditions, or jack up rates when a policyholder falls ill.

Obama took special pains to reassure senior citizens that Medicare cuts would not be used to finance the changes he is seeking - "not a dollar." Polls have shown opposition to reform strongest among those over 65 years of age, and they are the most reliable voters, particularly in nonpresidential elections.

Analysts say that one of the steepest challenges Obama faces is the sheer complexity of the subject. In a Pew poll this month, 67 percent said the health-care debate is hard to understand.

And the public is conflicted in what it wants. Though voters increasingly disapprove of how Obama is handling the health issue, there still is broad support for change. A CBS poll in late August found that four out of five Americans believe the health-care system needs "major changes."

With last night's speech, Obama gave himself a chance to clear up the confusion, and generate public support for his goals that will influence Congress to act.

Above all, he has to make sure he holds on to his liberal base, said Julian Zelizer, professor of history and public affairs at Princeton University.

"If he goes too far and the compromise is so meager that it's almost like doing nothing, that could trigger a backlash from supporters," Zelizer said. But he also has to be seen as effective and open to cooperation with opponents. Obama created his challenge by holding himself out as a transformational politician.

"If he looks just like the people he ran against, that would be very damaging," Zelizer said.

Contact staff writer Thomas Fitzgerald at 215-854-2718 or tfitzgerald@phillynews.com.