Tempestuous battles are brewing in two Northwest Side/northwest suburban Illinois Senate districts.

In one, Republican incumbent Dave Sullivan is quitting, sparking a nasty primary fight by a bunch of Republican lightweights, which could pave the way for a Democratic takeover. Against Sullivan, Democrat Dan Kotowski, former executive director of the Illinois Council Against Handgun Violence, would have had no chance. Against a lesser known, primary-bruised and cash-depleted Republican, he could win in 2006.

In another, one-term Democrat Don Harmon allegedly is quaking at the prospect that he may face a primary challenge from Mike Nardello, director of finance and administration with the city Department on Aging, who is a precinct captain in Alderman Bill Banks' 36th Ward Democratic Organization. Harmon's political base is shaky in Oak Park, where he is the Democratic committeeman, and he enraged Banks by opposing Banks' choice for Circuit Court judge in 2004.

Here's an early look at the contests:

33rd District (Park Ridge, Des Plaines, Mount Prospect, Elk Grove Village, Rolling Meadows, part of Arlington Heights and a few 41st Ward precincts in Chicago): Following the unexpected death of incumbent Marty Butler, Sullivan, of Park Ridge, was appointed to the Senate in December of 1998. At the time, he was an executive assistant to then-secretary of state George Ryan. In his 2000 bid for the remainder of Butler's term, Sullivan won with 60.5 percent of the vote, and he was re-elected in 2002 without opposition. Sullivan's record is staunchly conservative, and he was viewed as a contender for Henry Hyde's congressional seat, but state Senator Peter Roskam has already sewed up that nomination for 2006.

Sullivan, age 40, is not an attorney, and he does not earn outside income. He found that putting two kids through college on an annual salary of $60,000 was impossible, so he's retiring and is likely to take a lucrative private-sector job. He has offered to resign as soon as the local Republicans get their act together and decide on a replacement.

Each Illinois Senate district contains two House districts, and most House members are eager to move up to the Senate. The two state representatives in Sullivan's district are Republicans: Rosemary Mulligan (R-65), age 64, of Des Plaines, and Carolyn Krause (R-66), age 66, of Mount Prospect. Both are political "moderates," meaning fiscally conservative but pro-choice on abortion and liberal on other social issues. Either is a cinch to win the Senate seat, but neither will run. Both first elected in 1992, Mulligan and Krause are now senior House members, with prime committee slots; in the Senate they would be junior members of the minority party.

Without those heavyweights, the "Sullivan Succession" will be what one observer calls the "Battle of the Pygmies." Among those pondering the race are Des Plaines Mayor Tony Arredia, Arlington Heights Mayor Arlene Mulder, Elk Grove Township Republican Committeeman Cheryl Axley, Maine Township Republican Committeeman Mark Thompson, former Norwood Park Township Republican committeeman John Beniaris and Maine Township High School District Board President Eric Leys.

If Sullivan should resign, the district's Republican committeemen will choose his replacement. Back in 1990, after then-state senator Bob Kustra was elected lieutenant governor, Butler, then Park Ridge's mayor and the Maine Township GOP committeeman, had enough weighted votes to name himself. In the 33rd District, about 42 percent of the 2004 Republican primary votes were cast in Elk Grove Township, about 35 percent in Maine Township, and about 15 percent in Wheeling, where Scott Saewert is the committeeman. The remaining 8 percent were cast in Norwood Park and Schaumburg townships and the 41st Ward.

That means either (1) Thompson and Axley agree on who will be the senator, or (2) one of them makes a deal with Saewert to get his 15 percent, and thus a majority. If Thompson is the choice, his foes in Maine Township, where he challenged and lost to Supervisor Bob Dudycz in 2005, will back Arredia or Leys. If Axley is the choice, a Park Ridge primary contender will surely emerge, since a Park Ridge Republican has held that Senate seat for 30 of the last 40 years.

Mulder is deemed a strong contender, but she is not an active Republican, and she supports O'Hare expansion. Arredia won his second term as mayor in 2005, and he backed Dudycz over Thompson. Beniaris, of Park Ridge, who lost a bid for township supervisor in 2001, is the race's dark horse; he could be the least unacceptable nominee.

My prediction: Incumbency is meaningless unless it is used. If Axley or Thompson is appointed now, incumbency helps. If Sullivan doesn't resign until late 2005, incumbency matters not. The district is trending Democratic, and Kotowski has already raised $50,000; he will be unopposed for the Democratic nomination. If Republicans have a divisive, expensive primary and nominate a candidate unacceptable to one or more of their party's factions, Kotowski will win.

39th District (Oak Park, Northlake, Elmwood Park, River Grove, Franklin Park, Schiller Park, Melrose Park and parts of Bensenville, Stone Park, River Forest and the 36th, 41st, 29th and 37th wards in Chicago): Harmon, an obscure Oak Park lawyer, was hand-picked by Phil Rock in 2002 to be both the district's senator and Oak Park Township Democratic committeeman. Rock was then the committeeman, and he had been a state senator from 1971 to 1992 and the Senate president. Harmon was unopposed in the 2002 primary, and he was unopposed in the election, when the Republican candidate withdrew.

"He has never been tested," said Nardello. "He is not well known in the district, and he is not well liked in his Oak Park base."

The Senate district, created in 2001, is an electoral oddity. One state representative, Skip Saviano, is a Republican from Elmwood Park, and his 77th District is marginally Republican, while the other representative, Deborah Graham, is a black Democrat from the 29th Ward, where she was sponsored by Alderman and Committeeman Ike Carothers. Her 78th District is overwhelmingly Democratic.

The dividing line between the House districts is North Avenue. Graham's district contains 23 precincts in the black-majority 29th Ward and 15 in the black-majority 37th Ward. In the 2002 Senate primary they cast 5,466 votes and 2,742 votes, respectively. It also takes in 42 precincts in racially mixed Oak Park (which cast 7,688 votes for senator in 2002), seven precincts in River Forest (991 votes), and 22 black-majority and Hispanic-majority precincts in Proviso Township, including Melrose Park, Stone Park, Hillside and Northlake (2,498 votes).

And therein lies two interesting stories. First, Harmon and Carothers are political allies. In the 2002 primary for the newly created 78th District seat, Harmon backed Graham against another black woman, Dorothy Reid of Oak Park, and each candidate received 6,934 votes. A draw was held, and Graham was picked. Reid's Oak Park supporters have yet to forgive Harmon.

And second, in 2004, in the 11th judicial subcircuit, Banks backed Larry Andolino, claiming that it was "his turn" to pick a judge. Harmon backed Paula Daleo. After a bitter Democratic primary, Andolino triumphed by 36 votes, but Daleo filed a lawsuit alleging improper vote counting, and, in a surprise, just before the case went to trial, Andolino conceded. In 2006 Banks is again backing Andolino for a judgeship. Will Harmon defy him again?

As for Nardello, his chances are dependent on getting a huge vote in the 77th District, having Banks' endorsement, and cutting into Harmon's Oak Park base. Here's his strategy:

The 36th Ward has 10 precincts (Fullerton to North, between Nagle and Harlem), which cast 2,428 votes for senator in 2002. Nardello lives there, and he expects to get a huge vote. Leyden Township has 88 precincts, which cast 5,635 votes for senator in 2002; Nardello needs more than 80 percent of that vote.

The total turnout in the 2002 Democratic primary was 33,970, of which 26,699 votes were cast for the unopposed Harmon. Turnout likely will be about the same in 2006. So how does Nardello win? He needs 13,000 votes. If he gets 80 percent of the vote in Leyden and the 36th Ward, that gives him 6,500. He won't get more than 10 percent in the 29th and 37th wards, or 800 votes. So even if Nardello gets half of Oak Park's 7,688 votes, he's still about 2,000 votes short.

Nardello must run a dual campaign: He must attack Harmon as an Oak Park liberal in Leyden Township and the 36th Ward, and he must attack Harmon as an Oak Park traitor in Oak Park. He also must build an Oak Park precinct operation equal to Harmon's.

"He would need eight districtwide mailings (to win), and that would cost upwards of $300,000," said state Senator Jim DeLeo (D-10), a close ally of Banks. "He hasn't got it." DeLeo, an assistant Senate majority leader, said he is supporting Harmon, as is Banks.

My prediction: Given the district's demographics, Harmon's black base, and DeLeo's endorsement, Harmon's quaking is woefully premature. He will win in 2006.