U.S. President Barack Obama on Tuesday plans to unveil reforms aimed at thwarting future attacks like the attempted Christmas Day airliner bombing, as he seeks to limit political fallout from the incident.

Obama will outline an initial series of changes, including enhancements in much-criticized watchlists of terrorism suspects, after he meets with intelligence chiefs and other top security advisers, an administration official said.

On Obama's first full day back from his Hawaii vacation, he faces the challenge of spotlighting national security -- suddenly pushed to the top of his agenda -- while not looking distracted from other pressing public concerns like reducing double-digit unemployment.

It will be no easy task.

The administration is on the defensive after intelligence failures allowed a Nigerian with alleged links to Yemen-based al Qaeda operatives to board a transatlantic flight from Amsterdam on December 25. The man is accused of trying to blow up the plane with explosives hidden in his underwear.

U.S. spy agencies and the State Department had information about the suspect, 23-year-old Umar Farouk Abdulmutallab, but never connected the dots that might have put him on a no-fly list.

White House officials have conceded the failed bomb plot on a Detroit-bound airliner exposed errors that must be fixed but have played down the need for a top-to-bottom overhaul of the U.S. security system.

But Obama, who returned on Monday from 11 days in his home state, has been lambasted by Republicans who accuse his Democratic administration of being weak on terrorism and unable to fix intelligence gaps that have lingered since the September 11, 2001, hijacked plane attacks.

Republicans hope to score points for November elections to help challenge the Democrats' control of Congress.

YEMEN

With the U.S. military increasing forces battling Taliban insurgents in Afghanistan and burdened with continued responsibilities in Iraq, the failed Christmas attack has also raised doubts whether enough attention has been paid to Yemen, a poor, restive country at the tip of the Arabian peninsula.

Despite the administration and media focus on the bombing attempt, White House spokesman Bill Burton said he did not expect the issue to keep Obama from addressing jobs, healthcare reform and the rest of his agenda.

When you're president of the United States you've got to be able to walk and chew gum at the same time, Burton said on Monday.

It was clear, nevertheless, that national security issues and their domestic political ramifications would take up more of Obama's time than expected as he approached the one-year mark of his presidency.

The administration wanted to focus on economic recovery efforts and a job creation push after the holidays, in keeping with polls showing those issues topping Americans' concerns.

But Obama, who was criticized for waiting three days before making his first public statement on the airliner attack, now finds himself juggling a more complicated agenda as he tries to grab the initiative.

The administration on Monday imposed tighter screening for U.S.-bound airline passengers from Yemen, Nigeria and 12 other countries, including possibly being patted down, measures that civil libertarians called ineffective and unconstitutional.

After his regular briefings on Tuesday, Obama will meet at least 20 top officials to review what he has called human and systemic failures in the incident and how to avert a repeat.

Among those attending: Secretary of State Hillary Clinton, Defense Secretary Robert Gates, CIA Director Leon Panetta, Director of National Intelligence Dennis Blair, Homeland Security chief Janet Napolitano and FBI chief Robert Mueller.

After the meeting, the president will make public remarks (at 4 p.m. EST) outlining his findings and an initial series of reforms to improve our watchlisting system as well as our ability to thwart future attempts to carry out terrorist attacks, the administration official said.

(Editing by Doina Chiacu)

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