New York Sen. Hillary Rodham Clinton (D) raked in almost $4 million in the first three months of this year, setting a first-quarter fundraising pace that far outdistanced her 29 colleagues also seeking re-election in 2006.

Clinton, viewed as the leading potential Democrat in the 2008 presidential race, was one of at least 13 incumbents who raised more than $1 million in the quarter, newly filed fundraising reports showed. She was also one of 11 Senators who reported at least $2 million in available cash on hand.

Clinton increased her campaign war chest to $8.7 million as of March 31, although Republicans have no top-tier challenger currently on the horizon.

That fact didn’t stop Clinton from sending a congratulatory e-mail to supporters Monday, boasting about her stellar first-quarter start and reminding donors she still needs plenty of resources to fend off negative campaign attacks.

“Just as the right wing attack machines have started gearing up to defeat me in 2006, we’re sending a strong signal that we will be ready to fight back,” Clinton wrote.

Sen. Edward Kennedy (D-Mass.), another enemy of conservatives who is also unlikely to see a competitive re-election race, was the No. 2 fundraiser for the quarter among the 2006 class. He raised $2.1 million and increased his campaign coffers to $6.2 million.

Among Republicans, another Senator with 2008 White House aspirations topped the list of fundraisers for the quarter.

Virginia Sen. George Allen (R) took in almost $2.1 million in the period, leaving him with a little more than $3 million in reserves. Like Clinton, Allen is not likely to see a competitive re-election race this cycle and he is able to transfer funds from his Senate account for use on a presidential bid.

While some Democrats remain hopeful that Virginia Gov. Mark Warner will opt to challenge Allen next year, Warner, who is also a possible 2008 presidential candidate, is viewed as unlikely to do so.

Behind Allen, Sen. Rick Santorum (R-Pa.) had the next best fundraising quarter among Republicans. He raked in close to $2 million and showed $2.8 million in the bank on March 31.

Santorum, whom Democrats have already identified as their No. 1 target for defeat, is gearing up for an expensive, closely watched contest with state Treasurer Bob Casey Jr. (D). Casey, who formally announced his candidacy March 4, raised $90,000 in the four-week period and had $74,000 left in the bank.

Sen. Lincoln Chafee (R-R.I.), another top target for Democrats this cycle, didn’t fare as well when it came to stockpiling campaign cash last quarter (see related story, page 21). Chafee posted perhaps the most disappointing fundraising total of the quarter among all incumbents and was the only Senator outraised by a challenger in the period.

Chafee raised just $139,000 to $503,000 for Rhode Island Secretary of State Matt Brown (D). Former state Attorney General Sheldon Whitehouse (D) also recently entered the race and loaned his campaign more than $350,000 in start-up money.

Rounding out the list of top fundraisers for the quarter were several incumbents who may see competitive contests next year.

Sen. Maria Cantwell (D-Wash.) raised $1.9 million and ended up with $1.8 million in the bank after paying down all of her outstanding debt from her 2000 race.

Sens. Bill Nelson (Fla.) and Debbie Stabenow (Mich.), both potential GOP targets next year, each raised in the range of $1.1 million for the period.

Rep. Katherine Harris (R-Fla.), the most often-mentioned potential Nelson challenger, raised $411,000 and had $253,000 left in the bank.

Democrats remain hopeful that they will be able to mount an aggressive challenge to Sen. Conrad Burns (R-Mont.), who raised $925,000 and had $1.5 million in the bank. But there are no challengers in the race yet.

Likewise, Republicans are trying to lure North Dakota Gov. John Hoeven (R) into the race against Sen. Kent Conrad (D-N.D.), who raised almost $1 million in the quarter and had more than $1.7 million on hand.

But Republicans’ top recruiting priority of late has been in West Virginia, where 87-year-old Sen. Robert Byrd (D) is gearing up to run for an unprecedented ninth term. Byrd raised more than $1.1 million in the quarter, more than he raised during the entire 2000 election cycle.

The bulk of Byrd’s funds came from an e-mail solicitation written by Sen. Barack Obama (D-Ill.) and distributed nationally by the liberal group MoveOn.org.

Republicans are trying to entice Rep. Shelley Moore Capito (R-W.Va.) to run against Byrd, who has never faced a competitive re-election race. Capito raised just $72,000 in the first three months of the year and had $104,000 in the bank at the close of the period.

Meanwhile, a pair of Democratic House Members whom Senate leaders hope to coax into challenging incumbents next year showed meager fundraising totals to start the year, an indication they might not be looking to go anywhere.

Rep. Ted Strickland (D-Ohio), whom Democrats are wooing to run against Sen. Mike DeWine (R-Ohio), raised just $23,000 in the period and showed $456,000 in his campaign account. DeWine, meanwhile, raised $432,000 and had $2.4 million on hand.

Also on the Democratic wish list is a challenge by Rep. Tom Allen (D-Maine) to Sen. Olympia Snowe (R) in 2006. Allen, however, is considered unlikely to make the leap and his paltry $16,000 raised and $97,000 campaign war chest seem to support that notion.

Snowe raised $391,000 and had $760,000 left in reserve.

Several Senators who are currently not expected to face hotly contested challenges posted strong fundraising quarters as well. Sens. Joe Lieberman (D-Conn.), Jim Talent (R-Mo.), Jim Jeffords (I-Vt.) and John Ensign each raised $1 million or more.

Multimillionaire Sen. Herb Kohl (D-Wis.), who put retirement rumors to rest earlier this year, lent his campaign $2 million during the quarter. He traditionally has not raised much money, preferring to self-fund his campaigns.

In the open-seat race to succeed retiring Senate Majority Leader Bill Frist (R-Tenn.), Rep. Harold Ford Jr. (D) raked in $771,000 in the three month period — besting the totals of one other Democrat and the four Republicans seeking the seat. Ford has not officially declared his candidacy but is expected to make a run.

Meanwhile, several House Members continued positioning themselves financially in the event an open-seat race materializes.

In New Jersey, Sen. Jon Corzine (D) is running for governor and will appoint his successor if he is elected this November. Rep. Bob Menendez (D), one of the leading candidates to succeed Corzine, raised close to $1.1 million and ended March with more than $2.5 in the bank. He netted an additional $2.5 million at a fundraiser earlier this month.

In Texas, Rep. Henry Bonilla (R) is also ramping up his fundraising efforts as Sen. Kay Bailey Hutchison (R) continues to ponder a possible gubernatorial campaign next year.

Bonilla raised $791,000 and had more than $1.7 in his war chest at the end of last month. Hutchison, who is eyeing a primary challenge to Gov. Rick Perry (R), ended March with almost $7.3 million cash on hand — all of which she can use in a race for governor.

Sonny Bunch and Megan King contributed to this report.