Rivals-turned-friends John Warner and Mark Warner shared a walk up the Senate aisle Tuesday in a ceremony that marked generational and political change for Virginia.

Mark Warner, 54, a Democrat, wanted Republican John Warner, 81, to accompany him as he was sworn in. The two men are not related, but share an affinity that goes beyond their common surname.

"John Warner epitomizes what it means to be a senator," Mark Warner said in an interview after he took his oath. "He's been a great friend of mine, and I was so proud to have him there." Warner retired after a 30-year Senate career marked by bipartisanship. The younger Warner had mounted an unsuccessful challenge to the elder Warner in 1996, but they set that political history aside when Mark Warner became governor in 2002.

"I may be succeeding John Warner, but I'm not replacing him," the younger Warner told several hundred people at a Capitol Hill reception later Tuesday. "He is irreplaceable."

John Warner was greeted with a thunderous, sustained ovation when he took the podium at the reception.

"You see, Mark," John Warner cracked to laughter, "I should have run again."

John Ullyot, a former senior aide to John Warner, said the two men shared "a very close personal chemistry" and often teamed up on issues such as funding for military and transportation infrastructure.