Hillary Clinton was hoping to control the damage and John McCain was in search of affirmation as voters flocked to the polls for the so-called Potomac Primaries in Virginia, Maryland and the District of Columbia Tuesday.

Turnout was reportedly high, with voter interest projected to be surging on the Democratic side, as it has in other recent contests.

Barack Obama and McCain were the clear favorites going into the day’s primaries. McCain, the GOP front-runner, needs victories to rebound after suffering embarrassing defeats Saturday to committed underdog Mike Huckabee in Louisiana and Kansas.

A sweep Tuesday for Obama would seal a week-long shutout over Clinton for the Illinois senator, who is riding a wave of momentum off his five consecutive wins over the weekend.

Other region’s populations of well-educated, affluent, black voters favored Obama, exit polls in other primaries and caucus states showed.

Maryland and D.C. polls close at 8 p.m. ET, and Virginia polls close at 7 p.m. ET.

Clinton campaigned in the region, but was already directing her attention to delegate-rich Ohio and Texas, voting March 4, and was flying to El Paso later in the day. She’s banking on holding out until then to blunt Obama’s momentum in those primaries, which also include Rhode Island and Vermont. Several other states hold primaries ahead of the March 4 vote.

Supporters on both sides in the race cautioned that an Obama victory is not a foregone end to Tuesday’s primaries.

“You’ve got to be careful of these expectations … about tonight,” Obama supporter Sen. John Kerry told FOX News. “This is a contest, and he is running against the established machine of 20 years of effort in politics … nobody should take anything for granted.”

Obama stopped by a Dunkin’ Donuts in Washington, D.C., Tuesday morning with Mayor Adrian Fenty to pick up donuts and coffee to distribute to people holding campaign signs across the street.

Fenty, who’s supporting Obama, occasionally asked the crowd “Is D.C. for Obama?” and the crowd cheered in response.

Virginia Gov. Tim Kaine is also supporting Obama, while Maryland Gov. Martin O’Malley backs Clinton.

Asked if he thought he’d win Tuesday, Obama said he never expects to win until he wins.

“It’s very early,” Obama said. “We haven’t even gotten through this yet, come on, man,”

Massachusetts Rep. Jim McGovern, a Clinton supporter, said, “The conventional wisdom is that this is gonna be a tough day for (Clinton), but conventional wisdom has been wrong before.”

Obama was widely favored before the Jan. 8 New Hampshire primary, but Clinton ended up winning.

Clinton has faced down a streak of negatives headlines since Super Tuesday basically ended in a draw. She lost the weekend’s contests, she replaced her campaign manager Patti Solis Doyle and a New York Times story Tuesday said the Clinton campaign is scrambling to comfort anxious donors and superdelegates who fear her campaign may be slipping out of her hands.

Superdelegates are largely party officials who go to the convention unpledged to a candidate. The majority of those superdelegates who’ve said they are supporting a candidate have gone for Clinton, but even with those supporters included, her delegate lead was razor-thin going into Tuesday’s contests — 1,147, compared to 1,124 for Obama — in the race for the 2,025 delegates needed to win the Democratic nomination at this summer’s convention.

Since the Democratic primaries award delegates proportionally, if Clinton loses, she needs to lose by slim margins to retain an edge in the delegate count.

Democrats pick 168 delegates and Republicans 116 on Tuesday.

Obama was traveling late Tuesday to Wisconsin, which votes next week, along with Hawaii, where he grew up.

Clinton was doing satellite interviews with TV stations in Texas and Ohio. Astronaut and former Ohio Sen. John Glenn also endorsed Clinton Tuesday.

“I wouldn’t be doing this if I didn’t think I would be the best candidate,” Clinton told reporters Monday as she campaigned near Baltimore. “So I’m going forward — every day, we get to make our case to the American people.”

On the GOP side, McCain received warm greetings on the Senate floor Tuesday from some of his sharpest GOP critics. Sen. Thad Cochran, a Mississippi Republican who recently said the thought of McCain as the party’s nominee sent a chill down his spine, gave the Arizonan a big smile and hug.

“Congratulations,” called out Sen. David Vitter, R-La., who had endorsed Rudy Giuliani.

An Associated Press tally shows McCain had 729 delegates to Mike Huckabee’s 241 delegates. It takes 1,191 delegates to clinch the GOP nomination.

Areas like Norfolk, Va., have strong military populations, presumably favoring McCain.

“First and foremost we’re at war. John McCain would be a very credible, thoughtful and prudent leader … he doesn’t want to retreat and surrender in Iraq,” former Virginia Sen. George Allen told FOX News.

Since Mitt Romney dropped out of the race last week, McCain has been the favorite to win given his impressive delegate tally, but Huckabee has repeatedly pledged to stay in, saying he’s more into “miracles” than mathematical odds.

The former Arkansas governor’s wins over the weekend show he’s still got support among conservatives, a bloc with which McCain continues to mend fences.

Early turnout in Virginia was reportedly high and city officials in the District of Columbia were hoping that a swath of new registered voters would show up at the polls. Maryland election officials were also projecting a strong turnout, particularly in the Democratic race.

Virginia does not have party registration so voters can participate in either primary. By 9 a.m., voters had to wait as much as 45 minutes in some localities, Board of Elections spokeswoman Susan Pollard said.

“We have had heavy voter turnout in a variety of different localities throughout the state,” Pollard said. Richmond voter registrar J. Kirk Showalter said, “It’s a good strong turnout.”

Interest in the close Democratic contest was evident from spikes in voter registrations and absentee balloting in the region.

In Virginia, a total of 32,166 people had requested mail absentee ballots by last Tuesday’s deadline, and nearly two-thirds of them were for Democratic primary ballots. In the first two weeks of the year, 37,025 people met the Jan. 14 deadline for registering in time to vote in the primaries. Of that, 61 percent of the new registrants were age 24 or younger.

In the District, voter registration increased by 34,916 to 377,007 since the presidential primary in January 2004 — and is up more than 93,000 compared with the 2000 primary.

FOX News’ Bonney Kapp and The Associated Press contributed to this report.