President Obama addresses the nation Tuesday night at 8 ET with the latest on the BP oil disaster. Watch it live on CNN, CNN.com/Live and the CNN iPhone app.
Washington (CNN) -- President Obama must angle his address to the nation on the Gulf oil disaster as more of a "warlike update" than the kind of addresses given by past presidents on national tragedies, a top presidential historian said.
"This is going to be a different kind of president address ... like we're in the middle of the war and he's giving an update on the war on the Gulf," said Douglas Brinkley, a professor of history at Rice University. "It's a battlefield report -- particularly trying to show that progress is being made, although it's not fast enough for him."
Brinkley, who has lived and taught in New Orleans, Louisiana, has been a vocal critic of BP's cleanup efforts. He also has taken aim at Obama's response -- noting that he should have given the speech weeks ago.
"Whenever America experiences a cardiac arrest like 9/11 and the Oklahoma City bombing, you have a window of about one week where you want to create a field of optimism and a principle of response that it's clear, decisive and urgent."
The problem for the president, Brinkley said, is that he is addressing the country from the Oval Office while the crisis could continue for some time -- unlike when President Bush gave his address on the September 11 attacks and President Clinton's address on the April 19, 1995, Oklahoma City bombing.
The difference: The worst part of those two incidents, Brinkley pointed out, were over. The oil continues to gush nearly 60 days since the blast on the Deepwater Horizon rig -- and the cleanup efforts could continue for decades to come.
"President Clinton gave that speech and then the bad guys were caught. So there was a sense of closure," he said. "On 9/11 we had all these fears of more attacks. ... After about a week it was clear that the terrorist attacks were over."
He said that Clinton's Oklahoma City speech was brilliant and one of the "finest pieces of moving oratory."
"The bombing in Oklahoma City was an attack on innocent children and defenseless citizens," Clinton said in an April 20 address to the nation. "It was an act of cowardice and it was evil. The United States will not tolerate it. And I will not allow the people of this country to be intimidated by evil cowards."
In Bush's address to the nation on September 11, the focus was not only on what had happened -- but more so on the resolve of the American people and what steps the country was taking to retaliate at those responsible.
"Thousands of lives were suddenly ended by evil, despicable acts of terror," he said. "These acts of mass murder were intended to frighten our nation into chaos and retreat. But they have failed. Our country is strong."
And Bush's speech hit the hearts and minds of the American public.
"Tonight, I ask for your prayers for all those who grieve, for the children whose worlds have been shattered, for all whose sense of safety and security has been threatened. And I pray they will be comforted by a power greater than any of us. ..."
For Obama, the speech undoubtedly will be a three-parter: what occurred as a result of the explosion, the effects on the Gulf region and what steps the government is taking not only to help stop the leak but also the long-term plan to restore the region.
"We need the professorial Obama in the first two parts to explain what has transpired and where we are at this grim moment at time," Brinkley said. "In the third part of his speech, he needs to raise the bar and champion how much the Gulf of Mexico has given to America and the region will once again ride high."