Nine Republicans now serving in the U.S. Senate were once conservative Democrats.

They - including Sen. Orrin Hatch, R-Utah - all say the Democratic Party moved to the left, and left them behind. So they switched labels (even though most had been elected at some point as Democrats).If they all were still Democrats, that party would now control the Senate by a 54-46 margin - instead of the 55-45 majority that Republicans actually enjoy.

That shows how important conservatives or centrists could be to the Democratic Party - and the extra power it could achieve if it could lure back conservative-leaning centrists without offending the party's currently more liberal core.

It's the flip side to the problem more often mentioned in the national press that Republicans also have in attracting centrist support without upsetting and losing its solid right-wing.

The party switchers in the Senate include Strom Thurmond of South Carolina (a former Democratic governor elected to the Senate as an Independent Democrat); and Ben Nighthorse Campbell of Colorado and Richard Shelby of Alabama - who both switched after years in the Senate as Democrats.

Phil Gramm of Texas switched when he was a Democratic U.S. House member (and he says he never knowingly met a Republican until he was an adult).

Lauch Faircloth of North Carolina changed parties in 1991 before he was elected a senator in 1994.

Others who switched to become Republicans include Hatch, Wayne Allard of Colorado, Arlen Specter of Pennsylvania - and even current Senate Majority Leader Trent Lott of Mississippi.

Shelby - who switched parties the day after Republicans won back the Senate in 1994 - told "The Hill" newspaper recently, "The mainstream of the party was taken over by the left, until the left became the party mainstream. So you saw a renewal and dominance of the Republican Party in the South."

Shelby even says there's no longer such a thing as a conservative Democratic senator from the South. He said the last was Sen. Sam Nunn, D-Ga., who retired in 1996.

Hatch was the son of a construction worker who admired Democratic President Franklin D. Roosevelt - and Hatch also worked himself through law school as a (Democratic) construction worker.

But Hatch said he came to feel that Democrats and labor unions no longer truly worked for the working man, and he switched parties.

He later helped shepherd Campbell through a similar switch as a sitting senator. Campbell said he felt more and more like an outcast among a party controlled by liberals - and found Hatch and Republicans much more friendly and like-minded.

The exodus of conservatives and centrists from the Democratic Party in recent years has been significant. The National Republican Party reports that 363 elected Democrats (at local, state and federal levels) have switched to become Republicans since 1993 - or one about every five days.

Some conservative Democrats are still around - but "feel like an endangered species," said the last conservative Democratic House member from Utah, former Rep. Bill Orton.

He lost his seat two years ago after President Clinton misled him about creation of the Grand Staircase-Escalante National Monument - apparently because he wasn't liberal enough on environment issues to be trusted with plans for its surprise creation.

Orton is now the campaign chairman for another conservative Democrat, Steve Beierlein, who is running against Rep. Jim Hansen, R-Utah. Both were in Washington recently seeking support and money, and acknowledged it is tough in a party where liberal groups are now the core.

But such fights by Beierlein and other conservative Democrats may be the fight to save the party in the West and South.

Democrats own the political left (and maybe vice versa). To expand, they needs centrists. Unless Republicans do them the favor of running ultra-right extremists, the best way for Democrats to gain centrists is to run some - and listen to them.

Otherwise, people like the nine former Democrats who are now Republicans running the Senate will increasingly haunt them.