Obama's high command released the remarks as they struggled to bury the news of an embarrassing retreat on the party platform.

Under criticism from Republicans, they abruptly rewrote the day-old document to insert a reference to God and to declare that Jerusalem "is and will remain the capital of Israel." Some delegates objected loudly, but Los Angeles Mayor Antonio Villaraigosa ruled them outvoted.

Air Force One touched down as convention delegates filed early into the Time Warner Cable Arena, eager to nominate Obama and Vice President Joe Biden for new terms in time-honored roll calls of the states.

Obama's acceptance speech will mark the convention finale on Thursday night. Aides unexpectedly scrapped plans for him to speak to a huge crowd in a 74,000 seat football stadium, citing the threat of bad weather in a city that has been pelted by heavy downpours in recent days.

"We can't do anything about the rain. The important thing is the speech," said Washington Rey, a delegate from Sumter, S.C.

That and the eight-week general election campaign about to begin between Obama and Republican challenger Mitt Romney.

In a tight race for the White House and with control of the Senate at stake, Democrats signaled unmistakable concern about the growing financial disadvantage they confront. Officials said Chicago Mayor Rahm Emanuel, who was Obama's first White House chief of staff, was resigning as national co-chair of the president's campaign to help raise money for a super PAC that supports the president's re-election.

Unlike candidates, outside groups can solicit donations of unlimited size from donors. At the same time, federal law bars coordination with the campaigns.

Clinton's speech marked the seventh convention in a row he has spoken to party delegates, and the latest twist in a relationship with Obama that has veered from frosty to friendly. Whatever the past, the incumbent and his high command looked to the former president to vouch for him when it comes to the economy, his largest impediment to re-election.

Twelve years after leaving office, Clinton retains high popularity in the electorate in general as well as among white men who are dubious about giving Obama a second term in power in an era of slow economic growth and 8.3 percent joblessness.

As a group, white men favor Romney over Obama, according to numerous polls, but a Gallup survey taken in July showed 63 percent of them view the former president favorably, to 32 percent who see him in unfavorable terms.

White voters without college degrees preferred Clinton's wife, Hillary, over Obama in during their epic battle for the presidential nomination in 2008.

They now prefer Romney over the president by more than 20 percentage points, according to an Associated Press-GfK poll published last month, yet other surveys show they give high favorability to Clinton.

Clinton's turn on stage marked the second night in a row Obama ceded the convention spotlight. First Lady Michelle Obama delivered the featured speech on Tuesday night in a convention hall jammed with cheering delegates.

Republicans have suddenly discovered a lot to like about Clinton — a man they impeached in late 1998 when they ran the House and he sat in the Oval Office.

Ryan made no mention of those unpleasantries when he told a campaign audience in Iowa, "Under President Clinton we got welfare reform. President Obama is rolling back welfare reform."

"President Clinton worked with Republicans in Congress to have a budget agreement to cut spending. President Obama, a gusher of new spending."

Independent fact checkers have repeatedly debunked Ryan's claim about Obama's welfare proposals, repeated often in Republican television ads. Nor did the Wisconsin lawmaker mention that under a balanced budget compromise with Clinton to rein in federal spending, Republicans agreed to create a new benefit program that provides billions in health care coverage for lower-income children and others not eligible for Medicaid.

Democrats said their decision to move Obama's acceptance speech was due solely to weather concerns, adding they had too many people eager to attend, not too few as Republicans suggested.

Aides said Obama would hold a huge conference call with ticket-holders who would no longer be able to see the speech in person.

Party leaders did their best to draw as little attention as possible to the change in the platform, making the alternation even before the prayer that opened the second night of the convention.

The changes came after the Republicans questioned an earlier decision to strip the word "God" from the party's official platform.

Romney said that "suggests a party that is increasingly out of touch with the mainstream of the American people." "I think this party is veering further and further away into an extreme wing that American's don't recognize," he said.

In a summertime trip to Israel, Romney flatly declared Jerusalem was the country's capital. U.S. policy for years has held that the city's status is a matter for negotiations between Palestinians and Israelis, and Democrats said then that Romney was pandering to Jewish voters in the United States with his statement.

Under the Democrats' change on Wednesday, language from the 2008 platform was added to this year's version.

The switch on Jerusalem puts it in line with what advisers said was the president's personal view, if not the policy of his administration. "Jerusalem is and will remain the capital of Israel," it says. "The parties have agreed that Jerusalem is a matter for final status negotiations. It should remain an undivided city accessible to people of all faiths."

In more direct campaign matters, money is a constant concern for Obama's team, a turnabout from four years ago when their candidate vastly outspent Republican opponent John McCain.

Four years later, Romney is outraising Obama handily, and has pulled in more than $100 million three months in a row.

Outside groups eager to turn Obama out of power are pouring money into television advertising in battleground states at a pace that Priorities Action USA, the sole Democratic super PAC, cannot match.

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Associated Press writers Jennifer Agiesta and Jack Gillum in Washington, Kasie Hunt in Vermont, Thomas Beaumont and Steve Peoples in Iowa and Ken Thomas, Matt Michaels and Jim Kuhnhenn in Charlotte contributed.