WASHINGTON » President Barack Obama has been looking to historians for guidance on how to shape his second inaugural’s words into a speech for the ages, eager to make good use of his twice-in-a-lifetime opportunity to command the world’s attention.

Obama will seek to turn the page on a first term consumed by economic turmoil and set an optimistic tone for four more years that will help define his legacy.

The president has been working on his speech since early December, writing out draft after draft on yellow legal pads, aides say. He’s read several second-term inaugural addresses delivered by his predecessors. And last week he invited a small group of historians to the White House to discuss the potential — and the pitfalls — of second-term inaugurals.

Aides say the president will touch on some of the challenges he’ll take on in a second term but won’t delve deeply into the policy objectives he’ll tackle in the next four years. Those details will be saved for his Feb. 12 State of the Union address.

While Obama’s speech won’t be overly political, aides said he will make the point that while the nation’s political system doesn’t require politicians to resolve all of their differences, it does require Washington to act on issues where there is common ground. And he will speak about how the nation’s core principles can still guide a country that has changed immensely since its founding.

The president was still working on his speech heading into inauguration weekend. He’s hammering out details with longtime speechwriter Jon Favreau, who worked with Obama on his first inaugural address and many other high-profile speeches.

Obama’s dinner with the historians looked not only at the mechanics of second inaugural addresses, but also at how presidents manage second terms.

Perhaps more than any of his predecessors, Franklin D. Roosevelt’s second address could serve as a model for Obama.

Each man took office amid economic turmoil that eased during his first four years in the White House. When Roosevelt spoke to the nation after taking the oath of office a second time, he reported economic progress but cautioned that there was more work to do. Obama has often voiced similar sentiments, using the signs of improvement as his justification for re-election throughout the 2012 campaign.