to begin with, it's ASTOUNDING that the best scenario Cook foresees well might be possible, and even conservative! IMO, a net gain of anywhere between between 5 and 8 looks feasible.
A net pickup of six (with a D loss in NJ) would require a sweep of 5 "no clear favorite" seats currently held by Republicans, plus Santorum's D-leaning seat, plus a win for Webb over Allen in currently R-leaning Virginia. With a win by Menendez in currently "no clear favorite" NJ, we get to a gain of eight!
I'm using Congressional Quarterly's micropolitical analysis here:
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From
http://www.cqpolitics.com/risk_rating_senate.html"From Congressional Quarterly; Bob Benenson, Editor
Balance of Power Scorecard: Senate
*Open seat
Democratic Seats
----------------
9 Safe Democratic
(01) Calif. -- Feinstein
(02) Del. -- Carper
(03) Hawaii -- Akaka
(04) Mass. -- Kennedy
(05) N.D. -- Conrad
(06) N.M. -- Bingaman
(07) N.Y. -- Clinton
(08) Wis. -- Kohl
(09) W.Va. -- Byrd
5 Democrat Favored
(10) Conn. -- Lieberman
(11) Fla. -- Nelson
(12) Mich. -- Stabenow
(13) Minn. -- Dayton*
(14) Vt. -- Jeffords*
3 Leans Democratic
(15) Md. -- Sarbanes*
(16) Neb. -- Nelson
(17) Wash. -- Cantwell
1 No Clear Favorite
(18) N.J. -- Menendez
0 Leans Republican
0 Republican Favored
0 Safe Republican
Republican Seats
----------------
0 Safe Democratic
0 Democrat Favored
1 Leans Democratic
(19) Pa. -- Santorum
5 No Clear Favorite
(20) Mo. -- Talent
(21) Mont. -- Burns
(22) Ohio -- DeWine
(23) R.I. -- Chafee
(24) Tenn. -- Frist*
1 Leans Republican
(25) Va. -- Allen
1 Republican Favored
(26) Ariz. -- Kyl
7 Safe Republican
(27) Ind. -- Lugar
(28) Maine -- Snowe
(29) Miss. -- Lott
(30) Nev. -- Ensign
(31) Texas -- Hutchison
(32) Utah -- Hatch
(33) Wyo. -- Thomas
(For the purposes of this table, the Vermont Senate seat is counted as Democratic. Retiring Sen. James M. Jeffords serves as an Independent, but he is counted as a Democrat since he is allied with the Democrats and caucuses with the party in the Senate. Also, Rep. Bernard Sanders, who is the favorite to succeed Jeffords, serves as an Independent, but he is counted as a Democrat since he is allied with the Democrats and caucuses with the party in the House.)"