First of two parts.

The battle for control of the Senate is, in every way, a numbers game.

These numbers are indisputable: Republicans need to flip four seats held by Democrats in November to seize control of the Senate -- or just three if President Obama loses his re-election bid. Already the GOP is favored to take two seats of Democrats who are retiring: Sens. Ben Nelson of Nebraska and Kent Conrad of North Dakota.

If that isn't enough to make Democrats squirm, these numbers will: They're defending 23 seats this fall, many in difficult territory, while Republicans are defending just 10. The opportunities for Democratic pick-ups, it almost goes without saying, are far fewer than those that have presented themselves for Republicans.

But if money is the great equalizer, then the Democrats have some hope of retaining their majority. New fundraising reports released this week show most Democratic incumbents -- and a couple of challengers -- sitting on huge sums of money.

In a campaign finance environment run amok, with special interests and so-called Super PAC's now able to spend unlimited amounts to influence races, the fundraising totals of individual incumbents and challengers matter a little less than they once did. But a robust campaign war chest still illustrates an ability to compete vigorously, and on that front the Democrats are doing reasonably well.

More and more -- in contrast to 2010, 2008 and 2006 -- this is looking like a tight election cycle, where one party won't have a distinct advantage over the other. This means, on the Senate battlefield, that individual campaigns will matter more than nationwide trends.

Nine states are the first front in the war for Senate control. Here are the latest fundraising totals in those hyper-competitive states:

Florida

Sen. Bill Nelson (D), vying for a third term, is well set on the financial front. He finished 2011 with $8.4 million in the bank, after raising more than $1.3 million in the last three months of the year. His likely Republican challenger, Rep. Connie Mack IV, only got into the race in the fall, finishing the year with $918,000 on hand. But assuming Mack gets through his primary against former appointed Sen. George LeMieux (R) -- who had $1.1 million in his campaign account as of Dec. 31 -- he should be well-funded for the general election. The most recent public polls have shown Mack and Nelson essentially tied.

Hawaii

Ex-Gov. Linda Lingle is the Republicans' strongest candidate by far in the race to replace retiring Sen. Daniel Akaka (D), and she banked $1.4 million at the end of the year after raising almost $1.8 million from September to December. Rep. Mazie Hirono is battling former Rep. Ed Case for the Democratic nomination. She finished 2011 with a touch above $1 million in the bank and is now using the money on a TV ad that compares both Lingle and Case to George W. Bush. Case, who is running against the wishes of the powerful state Democratic establishment, raised $112,000 at the end of the year and banked $283,000.

Massachusetts

Two fundraising heavyweights continue to punch hard in a Democratic stronghold. Sen. Scott Brown (R), seeking to keep the seat he won after legendary Sen. Edward Kennedy (D) died, ended the year with almost $12.9 million in the bank after raising more than $3.2 million in the fourth quarter. His challenger, law professor and consumer advocate Elizabeth Warren (D) outraised him in the fourth quarter, taking in an eye-popping $5.7 million. She finished the year with less cash on hand, though: $6.1 million.

Missouri

A recent poll showed Sen. Claire McCaskill (D) tied with each of the three Republicans vying to run against her. But she continues to smoke all three on the fundraising front. McCaskill took in $1.4 million in the last three months, finishing 2011 with $4.8 million on hand. In comparison, businessman John Brunner (R) raised $1.2 million and banked $209,000 and Rep. Todd Akin (R) took in $232,000 and banked more than $1.1 million. The third Republican, former state Treasurer Sarah Steelman, raised $85,000 but had $573,000 in the bank.

Montana

The Treasure State remains a major Republican pickup opportunity, with Rep. Denny Rehberg (R) leading Sen. Jon Tester (D) in two recent polls. But the Democrat continues to hold a fundraising advantage. Tester took in almost $1.2 million in the last three months of 2011 and ended the year with $3.8 million in his campaign account. Rehberg banked $2 million after raising $656,000.

Nevada

After Massachusetts, the Silver State represents the Democrats' best hope for flipping a GOP seat, and appointed Sen. Dean Heller (R) and Rep. Shelley Berkley (D) are on equal ground from a financial standpoint. Heller took in a little more than $1.1 million in the last three months of the year and finished with more than $3.6 million in the bank. Berkley raised just shy of $1.1 million and banked more than $3.7 million. President Obama will run an active turnout drive in Nevada and Senate Majority Leader Harry Reid (D-Nev.) has a strong political operation. Democrats are hoping those prove to be the difference for Berkley.

New Mexico

Both parties have clear primary frontrunners in the race to replace retiring Sen. Jeff Bingaman (D), and that is reflected in the fundraising numbers. Among Democrats, Rep. Martin Heinrich raised $484,000 from September to December and banked almost $1.4 million, while state Auditor Hector Balderas collected $109,000 and banked $434,000. Ex-Rep. Heather Wilson, the choice of the Republican establishment, raised $375,000 in the last three months of 2011 and finished the year with $1 million on hand. Businessman Greg Sowards, who is trying to marshal tea party support to defeat Wilson, finished the year with $637,000 for his largely self-funded campaign, after taking in $169,000 in the fourth quarter. A third Republican, Lt. Gov. John Sanchez, has yet to report his fundraising numbers, amid rumors that he might leave the Senate race and run for the House seat that Heinrich is giving up.

Virginia

As in Montana, this is another clash of the titans where the Democrat has a slight financial edge for now. In the race to replace retiring Sen. Jim Webb (D), former Gov. Tim Kaine (D) raised $1.6 million during the last three months of 2011 and had $3.3 million in the bank. Former Sen. George Allen (R), seeking to win his old job back, raised more than $1 million in that period and finished the year with $2 million on hand.

Wisconsin

Republicans have a three-way brawl on their hands as they attempt to capture the seat now held by departing four-term Sen. Herb Kohl (D) -- whose personal wealth enabled him to campaign without raising very much outside money. Former Gov. Tommy Thompson raised the most among Republicans for the last quarter of 2011, taking in $657,000 and ending the year with $544,000 on hand. Former Rep. Mark Neumann, who has already lost bids for Senate and governor but is counting on tea party support, collected $518,000 and banked $552,000. State Assembly Speaker Jeff Fitzgerald raised $78,000 and finished 2011 with $73,000 in the bank. On the Democratic side, Rep. Tammy Baldwin, bidding to become the first openly gay member of the Senate, raised more than $1.1 million in the fourth quarter and finished the year with a campaign war chest of $1.8 million.

Coming Monday: Fundraising in the second tier of competitive Senate contests.