BOSTON - Republicans and Democrats were to come together at a private memorial service on Friday to honor Senator Edward Kennedy, the standard-bearer for liberal Democrats and patriarch of an American political dynasty.

The senator's body lay in repose in Boston where thousands of people gathered to pay their respects and preparations were under way to bury him on Saturday near the graves of his brothers President John Kennedy and Senator Robert Kennedy at Arlington National Cemetery outside Washington.

U.S. President Barack Obama was to give a eulogy during a funeral Mass at a Roman Catholic basilica in Boston on Saturday and three of the four living ex-U.S. presidents -- Jimmy Carter, Bill Clinton and George W. Bush -- were expected to attend. Former President George H. W. Bush, 85, was said to be unable to travel.

The Friday service was to bring together family members and longtime close friends such as former Republican presidential candidate Senator John McCain, Republican Senator Orrin Hatch and Democrats Vice President Joe Biden and senators Christopher Dodd and John Kerry.

Long lines formed outside the John F. Kennedy presidential library where the casket was on public view ahead of the memorial. Authorities closed the lines two hours earlier than planned, due to the large crowds.

As plans were being made for the memorial events, some conservative commentators warned Democrats against politicizing the death as a way to build momentum for an overhaul of the $2.5 trillion U.S. healthcare system, which has run into a phalanx of conservative opposition in the last month.

That struggle grew all the more difficult without Kennedy, a powerful advocate of health care reform who said providing health insurance to all Americans was the cause of my life. The issue is Obama's top domestic priority.

Some have suggested the party rally around the cause to honor Kennedy, who died of brain cancer on Tuesday at age 77. He had been in the Senate for nearly five decades.

But conservatives evoked the memory of the 2002 memorial service for Democratic Senator Paul Wellstone in 2002, which was transformed into a fervent political rally. Backlash was blamed for the loss of the Minnesota Senate seat

Talk show host Rush Limbaugh on his national radio show predicted Democrats would politicize Kennedy's death.

They can't help themselves because this is their religion, he said. This, liberalism, is their religion, and they are burying their pope.

Thomas Mann, senior fellow at The Brookings Institution, said that was unlikely. I doubt if Democrats are going to try to follow that model, they lost Paul Wellstone's seat as a consequence of it.

Kennedy's death, or putting Kennedy's name on the healthcare bill as some have suggested, was unlikely to have much impact on the debate, he added.

While Kennedy was considered a historic figure and was beloved by his Senate colleagues, most Republicans and conservatives still see him as the 'liberal lion,' Mann said. It's not as if he's this unifying, tremendously popular figure in the country. He's not.

SENATE VACANCY

Among those who lined up to view the casket was Laura Wernick, 54, an architect from Cambridge who said she wondered about the effect of Kennedy's death on health care reform.
It will be interesting to see what Obama says on Saturday, if he says we have to do this to honor his memory, she said.

Democrats worked this week to find a way to fill the senator's seat quickly, thus ensuring the votes needed to overcome Republican objections to a healthcare vote this year.

Kennedy requested Massachusetts lawmakers allow Governor Deval Patrick to name a temporary replacement to serve in his vacant Senate seat before a special election could be held.

Democratic leaders Senators Harry Reid and House of Representatives Speaker Nancy Pelosi were expected at Saturday's funeral along with some 40 other members of Congress and several cabinet members.

McCain, who had worked many years with Kennedy to reach consensus on controversial legislation, said on CNN's Larry King Live on Thursday Kennedy's wife Victoria had asked him to speak. And I told her I would move heaven and Earth, I would be there. And so I'm very honored to -- to have the opportunity to say a few words on behalf of the last lion of the Senate.

(Additional reporting by Tabassum Zakaria, Vicki Allen and Donna Smith in Washington, Ed Stoddard in Dallas and Ellen Wulfhorst in New York. Writing by Ellen Wulfhorst; editing by Jackie Frank)