Just three months after winning re-election on November 6, the Democratic president has a narrow window to push through policy priorities on the economy, immigration reform, and gun control.Analysts say he has roughly a year before Washington turns its attention to the 2014 mid-term elections, which could sweep more Republicans into Congress and accelerate the subsequent "lame duck" status that defines presidents who are not running for office again."He basically has a year for major legislative accomplishments because after the first year you get into the mid-term elections, which will partially be a referendum on his presidency," said Michele Swers, an associate professor of American government at Georgetown University.Obama's speech at 9:00 p.m. EST on Tuesday (0200 GMT Wednesday) will be a chance for the president to build momentum within that tight time frame."I don't want to say it's the last important speech he's going to give, but the window for a second-term president is fairly narrow," said Tony Fratto, a White House spokesman under former Republican President George W. Bush.With unemployment still high and massive "sequester" spending cuts looming, administration officials say Obama will use the address before a television audience of millions to press Congress to support his proposals to boost the economy.The White House is eager to show Obama's commitment to the economy is as great as it is to immigration and gun reforms, and he is expected to spend most of his speech reviving a theme that dominated his 2012 campaign: helping the middle class."You will hear ... an outline from him for his plan to create jobs and grow the middle class," White House spokesman Jay Carney said on Monday."His principal preoccupation as president has been the need to first reverse the devastating decline in our economy and then set it on a trajectory where it's growing in a way that helps the middle class, makes it more secure, and makes it expand."ECONOMY, LEGACYThe likelihood of passing new short-term economic initiatives that require government spending in the Republican-controlled House of Representatives is low, said Jeffrey Bergstrand, a finance professor at the University of Notre Dame and a former Federal Reserve economist."What will probably surface is something similar to what he proposed in 2011 and never got through," he said, referring to proposals that would give grants to state and local governments as well as boost spending on infrastructure and research.Obama is also expected to call for comprehensive trade talks with the 27-nation European Union.The White House has signaled Obama will urge U.S. investment in infrastructure, manufacturing, clean energy and education, despite Republican opposition to increased government spending and a political divide over how to tame the U.S. budget deficit.Obama's advisers argue that his push for immigration reform is also an economic issue, and momentum for change is stronger there than it is for the president's other policy priorities.Republican Senator Marco Rubio, a Cuban-American who is championing immigration reform - albeit with a more restrictive process of legalization than Obama supports - is slated to give his party's response to Obama's speech.The debate over immigration will also play out in the balconies of the House of Representatives, where non-lawmakers will sit to listen to the speech. Representative Luis Gutierrez of Illinois plans to bring a man who is fighting deportation as his guest to the speech.Prospects for success on gun control are in doubt, but the president is likely to use his speech to seek more support for proposals he laid out last month after the Newtown, Connecticut, school-shooting massacre.After giving prominent mention to the fight against climate change and equality for gays in his inaugural address, supporters will be disappointed if he fails to lay out details in those two areas. Obama could advance both issues through executive orders, circumventing Congress and doing more to bolster his legacy."A second-term State of the Union is usually written with an eye on history books and I'm sure the president is thinking about what his legacy is going to be," said Doug Hattaway, a Democratic strategist and former adviser to Hillary Clinton.Iran's nuclear ambitions and the festering civil war in Syria may present Obama with the toughest foreign policy tests of his second term, but they are likely to receive little attention in his speech.He might raise concerns about cyber attacks, which have hit a succession of major US companies and government agencies in recent months.Obama will travel to three states in the days after his speech to sell his proposals to the public.