Hillary Clinton is looking to score what may be her campaign's last hurrah in Sunday's Puerto Rico primary, a contest that is drawing rare attention to the island territory's political process.

With 55 pledged delegates, the Puerto Rico contest is the most valuable of the three primaries left on the Democratic calendar.

Polls show Clinton ahead in the race, a lead that reflects her overall support among Latino voters.

While Barack Obama has not been to Puerto Rico since last week, Hillary, Bill and Chelsea Clinton all have campaigned hard there and by Sunday will have visited 48 of the territory's 78 municipalities.

"It's like a carnival, it's just been fabulous," Clinton told FOX News Saturday. "This is an important primary to make sure that the interests and needs of the people of Puerto Rico are paid attention to, and that's what I'm trying to do."

On Sunday, the former first lady stopped by a San Juan baker called Kasalta, where she quickly shook some hands without working her way all the way back to greet everyone. Voting closes at3 p.m. ET.

Puerto Rico's 55 delegates, combined with the 31 total delegates at stake in the final South Dakota and Montana primaries Tuesday, aren't enough to eliminate Obama's daunting lead.

As of Saturday afternoon, Obama was nearly 200 delegates ahead of Clinton, though he was set back by the DNC rules committee's decision to count Michigan and Florida partially.

Though she won both contests, the states were initially stripped of all their delegates for holding early primaries. Clinton was looking for the delegations to be reinstated in full, but the DNC panel voted to seat the delegates with half their votes, which would not award Clinton a windfall of delegates.

The Democratic candidate must now get 2,118 delegates to be the nominee. Obama has 2,052 delegates. Clinton has 1,877.  About 205 superdelegates have not committed yet to a candidate.

"We have to win this fall. Hillary Clinton easily beats John McCain and for a lot of superdelegates and a lot of folks who are on the ballots, those are important considerations," Clinton campaign chairman Terry McAuliffe told ABC's "This Week."

Once primaries wrap up Tuesday, party leaders are pressing for a swift end to the race.

House Speaker Nancy Pelosi, Senate Majority Leader Harry Reid and DNC Chairman Howard Dean want uncommitted superdelegates to make up their minds and the Obama campaign claims it will achieve an official victory soon after Tuesday.

Obama has focused on the Tuesday primaries, campaigning in Montana on Friday and in South Dakota on Saturday.

In Montana, political observers and a statewide poll suggest Obama has the advantage. Montana polls close an hour after South Dakota polls, meaning a victory there would allow Obama to end the campaign on a symbolic high note.

But Clinton is still pressing her case to uncommitted superdelegates that she is the most electable candidate against presumptive GOP nominee John McCain, hoping they don't tumble into Obama's column once primaries end Tuesday and it is clear he is the pledged delegate leader. Either candidate would almost certainly need more superdelegates to clinch the nomination.

Clinton intends to build up her popular vote totals Sunday in Puerto Rico, amplifying her argument to those superdelegates that she is the popular vote leader.

She spent Saturday riding on a campaign caravan through Puerto Rico, waving to supporters from the back of a pickup truck.

"Campaigning in Puerto Rico is like one long Puerto Rican day parade," Clinton said in Caguas Saturday morning. "It is incredibly energizing, exciting."

She also said she wants Puerto Ricans to be able to decide their official status in the eyes of the U.S. government.

When it comes to the popular vote, Obama actually leads Clinton by nearly 450,000 votes in primaries and caucuses where delegates were at stake. That doesn't include caucuses in Iowa, Nevada, Washington, Maine and Texas, where party officials did not report any popular vote breakdown between the two candidates. Obama won all of those caucuses except Nevada.

Clinton claims the popular vote lead by including the results from Michigan and Florida, where no delegates were initially at stake. All Democratic candidates agreed not to campaign in those states, and Obama removed his name from the Michigan primary ballot. When the Michigan and Florida results are included, along with the nonbinding results in primaries in Washington, Nebraska and Idaho, Clinton has a 126,553 vote lead out of more than 35 million votes cast.

Puerto Rico is not part of the electoral college in the general election, so a victory there would do little for Clinton's argument that she's the better candidate for a general election.

Click here to read more about the Puerto Rico primary.

FOX News' Major Garrett, Aaron Bruns and Geraldo Rivera and The Associated Press contributed to this report.