Washington ? Senators are great glad-handers, not just with their constituents but with each other. Every time a vote is called, they mill around in front of the rostrum, grabbing hands and shoulders, or patting each other’s back.

But, as my colleague Dana Milbank noted, it was a poignant moment last week when Ted Stevens of Alaska, newly indicted for accepting unreported favors from an oilman friend, walked over to Robert Byrd of West Virginia, who uses a wheelchair because of age and illness, in search of support and consolation.

Stevens, 84, is a Republican, and Byrd, 90, a Democrat. But their bonds are far stronger than any partisan differences. In their decades of service, they dominated the Appropriations Committee, passing the chairmanship back and forth between them, depending on which party held the majority.

Both men have become famous – or notorious – for using their committee posts to steer billions from the Treasury to their home states, defying their colleagues who call them “kings of pork.” They represent, if not the last, certainly the rear-guard of a generation of senators who see it as their principal responsibility to help their chronically needy citizens obtain the federal largesse that can spell the difference between subsistence and a decent living.

But as the Senate contemplates another election in November that will likely bring dramatic generational change, Stevens and Byrd are reminders of the changing culture of that body.

Veteran Republican senators are retiring this year in Virginia, New Mexico and Colorado, among other states, and all three may well be replaced by Democrats.

Stevens’ re-election now is in doubt and if you throw in New Hampshire, where young John Sununu, one of the ablest of the Republican underclassmen, is facing a stiff challenge, you can see why Democrats are talking up their prospects of markedly expanding their current shaky two-vote Senate margin.

At a briefing I attended the other day, Sen. Charles Schumer of New York, the chairman of the Democratic Senatorial Campaign Committee, said it would be “difficult” to reach the 60 seats that would stop Republican filibusters. “But it’s not out of the question,” he said, even though it would require the Republicans to lose nine races.

As significant as the numerical potential is the changing character of the new senators who may arrive in this election. They could be welcome news for either a President Obama or a President McCain, because the likeliest winners are mainly centrists who have been tested in real-world politics and have little tolerance for ideological extremes.

Two of the top five Democratic prospects are people who have been governors of conservative states. Sununu is in a rematch with former New Hampshire Gov. Jeanne Shaheen, who dealt with a Republican Legislature throughout her tenure in Concord and – to the disappointment of some Democrats – managed to avoid a new broad-based tax to finance the schools.

The other former governor is Mark Warner of Virginia, favored to succeed retiring Sen. John Warner (no relation). Mark Warner, a millionaire businessman, also shared the capital with a Republican Legislature and learned in his four years a wealth of practical wisdom about negotiating compromises. That description also fits Mark Begich, the mayor of Anchorage, who is the likely Democratic nominee for Stevens’ seat.

The last two on Schumer’s list of top prospects are the Udall cousins, part of a Democratic dynasty that goes back more than a half-century. Tom and Mark Udall are the sons of Stewart and Morris Udall, who between them held the Tucson-area Arizona House seat for decades.

Mark and Tom serve together in the House, from Colorado and New Mexico, respectively. Mark has the more liberal district and voting record, but neither would ever be mistaken for a New York City congressman. The Republicans have put forward candidates more conservative than the retiring GOP senators and are underdogs in both races.

These five are likely recruits for the growing band of senators who – under McCain’s leadership – saved the Senate from blowing up over the issue of judicial filibusters. If McCain and Obama are serious about moving beyond partisan gridlock, these folks might help.