* Gun-rights advocate Reid will decide what Senate will vote on
* Reid has expressed doubt about ban on assault weapons
* Senate may focus on measures that could pass Republican-led House
WASHINGTON, Jan 16 (Reuters) - What will Harry Reid do?
As President Barack Obama's gun-control package heads to the U.S. Congress, one of the big questions hanging over Capitol Hill is how Reid - a fellow Democrat and the Senate majority leader - will manage the most ambitious proposal for gun restrictions since the 1960s.
In the political drama likely to play out over guns, Reid is hardly the gun-control advocate from central casting. Like many Republicans and several fellow Democrats from conservative states, Reid, 73, has often opposed limits on gun owners.
He was endorsed for re-election by the pro-gun National Rifle Association in 2004, though not in 2010. He has voted to protect gun makers from lawsuits (2005) and supported allowing firearms in checked baggage on Amtrak trains (2009).
But the Nevada Democrat has also supported various calls for more background checks of prospective gun buyers.
Expanding such checks is a focus of Obama's plan, which also includes proposals for a ban on the sale of military-style assault weapons, a new federal gun-trafficking law and a 10-round limit on ammunition magazines.
Many lawmakers and analysts believe a ban on assault weapons is unlikely to clear Congress, and that Obama's proposal will probably be whittled down significantly before a version of it can be passed.
They said that in the Republican-led House of Representatives, getting a vote on any gun legislation could be difficult. And in the Democrat-led Senate, they said, it all depends on Reid, who as majority leader decides what legislation makes it to the floor.
As recently as Sunday, Reid expressed doubt about an assault weapons ban and suggested that expanding background checks would be a more realistic goal.
"Is (a ban on assault weapons) something that can pass the Senate? Maybe," Reid said in an interview with a PBS television affiliate in Las Vegas. "Is it something that can pass the House? I doubt it."
REID A 'SMART GUY'
On Capitol Hill, Reid's message was interpreted to mean that he would not ask Senate Democrats to support the assault weapons ban, or other measures that would anger conservatives in their home states, if those measures had no chance of passing the House anyway.
"Reid doesn't want to expose members to votes on bills that might not even be brought up for a House vote," said a senior Democratic aide who was not authorized to speak publicly. "But some of his own Democrats may introduce their own bills to ban assault weapons and push for votes on it."
Larry Sabato, heads of the University of Virginia Center for Politics, agreed that Reid was "positioning himself to only pass things in the Senate that can pass the House."
A senior Republican aide, who asked not to be identified, predicted Reid was unlikely to call a Senate vote on an assault-weapons ban unless it were filled with loopholes.
"Harry Reid is a smart guy," the aide said. "To gun activists, banning assault weapons sounds too much like, 'The government is trying to take away my guns.' It is not going to fly."
After Obama announced his plan on Wednesday, Reid said he was "committed to ensuring that the Senate will consider legislation that addresses gun violence and other aspects of violence in our society early this year."
Reid added that "all options should be on the table moving forward."
SOME DEMOCRATS ANXIOUS
Polls indicate that after the massacre of 20 children and six adults last month at a school in Connecticut, most Americans want restrictions on the type of rapid-firing "assault" rifle that was used in the shootings.
Illinois Representative Bobby Rush, a Democrat who became a gun-control advocate in 1999 after his teenage son was gunned down in Chicago, said Reid was part of the reason he fears Obama's efforts may come up short.
"I see Democrats like Harry Reid never in favor of meaningful gun legislation," Rush said.
"Reid should bring (a proposed ban on assault weapons) for vote and see what happens," Rush added. "If there are enough agitated Americans who make their voices heard, they can move this Congress."
In the Senate, the gun legislation will originate in the Judiciary Committee. The panel's chairman, Vermont Senator Patrick Leahy, said on Wednesday that the first hearing on Obama's gun proposals would be on Jan. 30.
If the committee winds up approving an assault weapons ban and Reid does not allow a vote on it, "I'd be very disappointed," said Democratic Representative Jim Langevin of Rhode Island, a long-time backer of banning assault weapons.
And, Langevin said, "so would a lot of other Democrats."