For Illinois' 59 state senators, bigger is not necessarily better, and longer is not necessarily safer.

Each Illinois Senate district has a voting age population of between 150,000 and 200,000, and each encompasses two House districts. Over a 10-year cycle, a senator is elected to two 4-year terms and one 2-year term, running three times; in contrast, representatives are elected every 2 years in districts half the size, running five times. By running less often and in a larger area, senators are potentially more vulnerable than representatives.

Which gives rise to the "Carroll Syndrome," named after former state senator Howie Carroll, a phenomenon that haunts many senators, particularly those from Chicago. Carroll, a Democrat, was elected to the Senate in 1972 and was re-elected seven times, always by overwhelmingly margins, in his Northwest Side district, which included the 50th, 40th, 39th and 45th wards and parts of suburban Lincolnwood and Skokie. He was a powerful player in Springfield, as part of the Democratic leadership and as chairman of the Appropriations I Committee, which oversaw state government funding.

But, back in his district, Carroll was cloaked in obscurity, which was demonstrated in 1998, when he ran for Congress in the 9th U.S. House District after Sid Yates retired. Carroll, after 26 years in the Senate, from a district covering about half of the congressional district, should have been a cinch to win, but in a three-way race he finished a disappointing second to Jan Schakowsky, a state representative from Evanston. Schakowsky won almost 77 percent of the vote in her House district, which was only a quarter of the congressional district, while Carroll didn't even win half the vote in his Senate district.

The clear message in Carroll's demise: Senators may think of themselves as part of the political elite, but voters rarely think of them at all. Longevity does not ensure popularity or recognition. And if some ambitious, self-funding candidate decided to dump $300,000 of his or her own money into a primary or an election campaign, there is not a single Illinois senator who wouldn't be in serious jeopardy.

The Democrats currently have a 32-27 Senate majority, and that may increase in 2006 due to the retirement of several suburban Cook County Republicans, including Dave Sullivan (R-33) of Park Ridge. The adjoining vote chart details the record of area senators, including suburbanites Sullivan and Don Harmon (D-39) of Oak Park, as well as Chicagoans Ira Silverstein (D-8), Jim DeLeo (D-10), John Cullerton (D-6) and Iris Martinez (D-20). The seats of Harmon, Sullivan, DeLeo and Cullerton are up in 2006; Silverstein and Martinez were re-elected to 4-year terms in 2004. Here's the outlook for next year's races:

10th District: DeLeo, age 54, is an assistant Senate majority leader, and he was re-elected without opposition in 2002; his political base is in Chicago's 36th Ward, where he is a close ally of Alderman and Committeeman Bill Banks. For 10 years, from 1992 to 2002, he represented a Senate district that ran from Cumberland to Kedzie, between Lawrence and Fullerton. In the Democratic-designed 2001 remap, DeLeo and fellow incumbent Wally Dudycz, a Republican, were put in the new 10th District, a Christmas-tree shaped district which runs from Belmont to Dempster in Niles, between Keeler and Cumberland, taking in the 41st, 36th, 38th and 45th wards plus Norridge, Harwood Heights and Niles. That was a district that Al Gore won in 2000 with 58 percent of the vote and that Rod Blagojevich won in 2002 with 58 percent. Dudycz knew he couldn't beat DeLeo, and he retired.

But that doesn't mean DeLeo is secure. He votes like a conventional Democrat, supporting gun control, opposing medical malpractice and workers' compensation reforms, and backing the 2006 budget. However, he has a huge skeleton in his proverbial closet: Back in the 1980s, while he was working for the Cook County Circuit Court clerk, DeLeo was indicted by the U.S. Attorney's Office for allegedly taking bribes and falsifying his income taxes. The trial ended in a mistrial. At the time of trial, DeLeo was a state representative. Instead of a retrial, the feds offered DeLeo a deal: plead guilty to one count of misdemeanor tax offense and pay a fine and back taxes. DeLeo did so, and because he wasn't convicted of a felony, he didn't forfeit his House seat.

DeLeo's greatest fear is that some self-funding, Irish-surnamed Democrat will take him on in a primary and run a nasty, negative campaign. Like Carroll, DeLeo is largely unknown in the 10th District, and he could be easily defined in a negative fashion by an astute opponent. DeLeo is already taking steps to correct that situation: He is planning to spend close to $100,000 on five districtwide mailings over the next 6 months, the first of which was a legislative newsletter delivered in July. The outlook: No Democrat has yet surfaced to take on DeLeo.

6th District: Cullerton, age 56, is a political institution in his Lakefront district, which runs between Lawrence and Armitage, west to Sacramento. He has served in the Senate since 1990, and he was a House member for 12 years. He was unopposed in the primary in 2002, and he won the 2002 election with 69.9 percent of the vote. Cullerton ran for Congress in 1994, losing in the primary. He is currently chairman of the Judiciary Committee, is safe in his district, and likely will serve for many more years.

39th District: Harmon, age 38, was plucked from obscurity in 2002 by retiring Oak Park Township Democratic committeeman Phil Rock and handed both the Senate seat and the committeemanship on a silver platter. The district takes in parts of the 36th and 29th wards in Chicago, plus Oak Park, River Forest, Melrose Park, Elmwood Park, River Grove, Franklin Park, Northlake, Schiller Park and part of Bensenville. Harmon was unopposed in the 2002 primary, and he got 70.3 percent of the vote in the election. Harmon is a liberal Democrat, and his great worry is a primary challenge. He has not yet entrenched himself.

33rd District: Sullivan, age 40, is retiring for financial reasons, saying that he cannot put his kids through college on his legislative salary. He was unopposed in 2002, but Democrats plan to make an effort to win the seat in 2006. However, this was a district that Jim Ryan won with 61 percent of the vote in 2002, and Democrats are definite underdogs, unless the Republicans engage in a divisive primary and nominate a weak candidate. The district contains Park Ridge and the northwestern suburbs stretching to Rolling Meadows. Democrat Dan Kotowski is running, and the Republican field is still forming.

Not on the ballot on 2006 are Silverstein and Martinez. Silverstein, age 44, is the chairman of the Executive Committee and is regarded as a comer in Springfield. His base is the 50th Ward, and he won Carroll's seat in 1998, triumphing in the primary by 844 votes, with 41.5 percent of the total. But he was elected comfortably, winning with 68.3 percent of the vote in 1998, 69.3 percent in 2002 and 71.1 percent in 2004. He aspires to run for Congress, but his path is blocked by Schakowsky.

Martinez, age 49, was elected in her 53 percent Hispanic-majority district in 2002, defeating Alderman Mike Wojcik with 61.5 percent of the vote. She was heavily supported by the Hispanic Democratic Organization, which sent hundreds of workers into the district. However, the HDO is currently mired in the city's Hired Truck scandal, and it may soon be but a memory. Martinez was renominated and re-elected without opposition in 2004, but without the HDO, she could be vulnerable in the future.