Officials in Washington D.C., Maryland and Virginia are anticipating a huge turnout of voters in Tuesday's presidential nomination contests in their region, known as the "Potomac Primary."
The voters' enthusiasm was sparked by the fact this year's nomination races in their hometowns offered a rare chance that the three regions could influence the whole nomination process.
In the U.S. capital, voter registration increased by 34,916 to 377,007 since the presidential primary in January 2004, according to election officials of Washington D.C.
In Maryland, turnout was anticipated to be about 40 percent, which is above normal, according to Ross Goldstein, deputy administrator for the state's Board of Elections.
Virginia election officials also predicted a higher than normal turnout of 30 to 40 percent for the state's primaries.
At stake in the primaries are 238 Democratic delegates and 119 total GOP delegates.
Polls in Maryland and the District of Columbia close at 8 p.m. (0100 GMT Wednesday) and in Virginia at 7 p.m. (0000 GMT).
On the Democratic side, the key question is whether Sen. Barack Obama (D-Ill) will be able to sustain the momentum he mustered in his sweep of five Democratic contests last weekend.
The devil is in the demographics for Democrats.
Maryland, Virginia and Washington DC have large numbers of African-American and affluent white voters.
Obama has fared well against opponent Hillary Clinton (D-NY) in the past with both groups.
In total delegates, Clinton tops Obama 1,157 to 1,145, according to CNN's tally.
The breakdown paints a slightly different picture, as Obama leads 989 to 923 in pledged delegates, and Clinton is winning among superdelegates 234 to 156.
Superdelegates, a group of 796 Democratic Party officials and leaders, are not required to make their votes public and are free to change their minds.
In the Republican race, the question is whether Sen. John McCain can start to unify the Republican party behind his all-but-certain nomination.
McCain is leading the only other Republican candidate in the race, former Arkansas Gov. Mike Huckabee, 723 to 217 in total delegates, according to CNN's tally.
A GOP candidate needs 1,191 delegates to secure the nomination.