WASHINGTON (Reuters) - With support for his Iraq policies at an all-time low, President Bush will deliver a prime-time speech on Monday seeking to assure the public he has a strategy for handing over power to Iraqis and keeping the violence from spiraling out of control.

Bush and his aides are also stepping up outreach to key members of the United Nations to support a new resolution that will shape post-occupation Iraq.

The November presidential election could be profoundly influenced by what happens in Iraq, beginning with the five weeks that remain before the transfer of limited authority to an interim Iraqi government on June 30 and the immediate aftermath.

Monday night's speech at the Army War College in Carlisle, Pennsylvania, marks the start of a public relations campaign designed to shore up Bush's standing and draw the public's attention from bloodshed to the transition.

But that could be a tough sell at a time when the American death toll is rising, the Abu Ghraib prison abuse scandal is spreading and the White House is publicly acknowledging that the level of violence could increase after the June 30 handover.

"Part of the problem ... that we have here, after more than a year in Iraq, is a credibility and trust issue," Republican Sen. Chuck Hagel of Nebraska, a Vietnam veteran and a leading voice on foreign affairs, told CNN.

The stakes are enormous for Bush, presidential historian Doug Brinkley said. With his public standing "heading into a downward spiral, it is imperative that the president appeal directly to the American public. It's one of those moments historians will look at decades from now," he added.

In Monday's speech, which will be carried live by the cable networks at 8 p.m. EDT (0001 GMT), Bush will outline U.S.-backed plans to establish an interim government that would pave the way for free elections.

Bush is responding to opinion polls and public pressure from fellow Republicans, including Senate Foreign Relations Committee Chairman Richard Lugar of Indiana, who urged the president to provide specific details and not just "generalization."

Similarly, Sen. Evan Bayh, an Indiana Democrat, told ABC's "This Week" that the nation needs to hear a "comprehensive strategy for success," adding, "I think that's one thing the American people feel has been lacking."

Bush on Monday is also expected to detail plans for a new U.N. Security Council resolution that the U.S. hopes will encourage other countries to commit troops to the post-occupation effort.

The administration plans to begin circulating a draft resolution later this week.

Bush, who initially shunned the United Nations, is now relying heavily on the world body to set up the caretaker government, and expects U.N. envoy Lakhdar Brahimi to name the country's interim leaders within the month.

The new public relations campaign underscores the administration's concerns mounting violence in Iraq will jeopardize Bush's re-election chances.

His approval ratings have slipped to the mid-to-low 40 percent range, the lowest of his presidency. No recent president has been re-elected with such numbers this close to the November elections.

"There isn't panic, but there is considerable concern," one senior Republican aide said.

Aides said Bush's goal is to show Americans, who have been focused on the violence, that he has a strategy to turn things around. Bush met with Republican lawmakers last week and is expected to deliver at least six presidential speeches on Iraq before June 30.

On the eve of Monday's speech, retired Marine Gen. Anthony Zinni, former chief of U.S. Central Command, accused senior Pentagon officials of failure in executing the Iraq war and told CBS' "60 Minutes" they should resign.

While Bush has not personally admitted mistakes, some of his top aides have recently acknowledged misjudging the level of violence that would sweep Iraq a year after the war began.

"It is not an easy task," White House spokesman Scott McClellan said last week.