With victories in 12 of the 14 primaries already under his belt, a euphoric Kerry later declared that Americans across the country were voting for a change.
"Americans are voting for change, east and west, north and now in the south," Kerry told cheering supporters.
The Virginia and Tennessee victories were significant and sweet since prominant rivals John Edwards and Wesley Clark had proclaimed the southern states to be their bastions.
But the twin victories on Tuesday - Kerry's first in the southern states - would expectedly help Kerry in portraying himself as the only Democratic candidate with a national appeal.
"Together across the south, you have shown the mainstream values that we share. Fairness, love of country, a belief in hope and hard work are more important than boundaries or birthplace," Kerry said.
Kerry's emphatic victories could effectively destroy the campaigns of rivals like John Edwards and Wesley Clark.
Both sons of the south, Edwards and Clark had argued they were better placed to take the battle to Bush in crucial conservative southern states than Kerry.
But Tuesday's results proved their claims to be hollow.
Kerry later said it was not up to him whether the rivals should stay in the race.
"Americans are voting for change, east and west, north and now in the south"
Democratic presidential aspirant
Bolstered by the wins, Kerry launched a broadside at President George Bush he intends to challenge in the presidential vote in November.
"How can we trust President Bush to create 2.6 million jobs when he has the worst record since Herbert Hoover when it comes to the national economy," he declared.
"For more than three years this administration has failed to tell the truth about the economy of our country," he said.
Kerry said Bush had made America "weaker by driving away our allies and breaking friendships and relationships around the planet."