SPRINGFIELD - Judy Baar Topinka continues to pose the most serious Republican threat to Democratic Gov. Rod Blagojevich, still holding him under 50 percent support among likely voters, according to a new Southern Illinoisan/Lee Newspaper poll.

But two weeks out from the GOP primary for governor, Topinka herself faces a growing threat from fellow Republican Jim Oberweis. The wealthy dairy owner has made substantial gains against her in the past month as he has stepped up an attack campaign, the poll indicates.

Meanwhile, even as politicians in Springfield continue to debate several hot-button social issues, the data show Illinoisans have largely made up their minds: By overwhelming majorities, poll respondents favored stem-cell research, unfettered access to birth control, and a proposed statewide public smoking ban. The telephone poll of 800 likely voters was conducted last Monday through Wednesday by Research 2000, a Maryland-based firm. The poll has a general margin for error of 3.5 percent, with higher margins for those questions asked just of Democrats or Republicans. The poll found that Topinka, Illinois' state treasurer, continues to hold a strong lead over four other Republicans going into the March 21 primary - and that she is the only candidate within striking distance of Blagojevich in head-to-head matchups.

"There's no question Blagojevich is vulnerable. He's under 50 percent - that's the bottom line," said Del Ali, who conducted the poll for Research 2000. "If Topinka rides out this storm (in the Republican primary), it could be a very interesting general election."

However, the primary may be a rougher storm for Topinka than it previously appeared. In a five-way race, the poll found Topinka is still comfortably ahead of second-place candidate Oberweis by a 36 percent to 25 percent margin. But that lead has shrunk significantly since early February, when a Chicago Tribune poll put Topinka ahead of Oberweis 38 to 17 percent.

Topinka is campaigning as a fiscal conservative and a social moderate, traditionally the most successful combination for Republican candidates in Illinois general elections - though hard-right conservatives such as Oberweis have often found success in GOP primaries. Oberweis has been in attack mode lately in his commercials and public appearances, going after Topinka on decade-old questions about two state-financed hotels and publicizing allegations of document-shredding from a former Topinka underling.

"It's tighter than it was, which you would expect, given the money that Oberweis … (has) spent," said Kent Redfield, a political expert at the University of Illinois at Springfield.

"She's certainly in a good position, still," Redfield added, noting that the small remaining cache of "undecided'' Republicans - 8 percent - would have to swing entirely to Oberweis for him to stage an upset at this point. "If the dynamics don't change dramatically, she's going to win. But I wouldn't be surprised if it tightens up a little more."

The poll also asked about matchups between Blagojevich and each of the five Republican candidates. Blagojevich won in all those pairings, but his closest race, against Topinka (47-40 percent) is right at that edge of the poll's margin for error.

"This should give credence to her position that if you're going to elect a Republican statewide in Illinois, you need a moderate," Redfield said.

Meanwhile, the poll indicates Blagojevich, after three years as governor, is still having trouble getting even his fellow Democrats solidly behind him. His overall favorable-unfavorable numbers are roughly even, tied in the mid-40s. Perhaps just as daunting, only 62 percent of registered Democrats give him positive performance marks.

For Democratic respondents like Cindy Slater of Moline, gender and regionalism trump party loyalty: She supported Topinka in the matchup with Blagojevich.

"She's a woman, I'm a woman," Slater said. "He's kind of arrogant. He lives in Chicago (instead of occupying the Governor's Mansion in Springfield). What is that about? I think that's disrespectful."

Others are skeptical about Blagojevich's generous election-year state budget, laden with proposals for universal preschool, college tuition tax breaks and other middle-class gifts.

"He's trying to be all nicey-nice because of the election. I don't trust him," said Corrina Engle of Collinsville, a Democrat.

That distrust may help explain why Blagojevich's challenger in the Democratic primary, former Chicago alderman Edwin Eisendrath, is peeling off about 26 percent of the Democratic vote, according to the poll. That's not likely a threat to Blagojevich in the March primary, but certainly is an embarrassment, given that Eisendrath is virtually unknown.

Despite Democrats' problems, Illinois is still very much a "blue state" in terms of the issues being debated in Springfield lately, the poll found. More than two-thirds of respondents said they favor state-funded stem-cell research, a Blagojevich initiative that conservatives oppose. Roughly as many respondents don't like a conservative proposal to allow pharmacists to refuse to fill prescriptions for "morning-after" birth control pills, which some believe causes a form of abortion.

"The issues that are important to voters (in Illinois) are Democratic issues," said Ali, the pollster. "If the Republicans want to win back the Governor's Mansion, they really have to put up a Jim Edgar-type candidate, a moderate. If they put up another cultural conservative . . . they're not going to get much more than Alan Keyes did" in his disastrous 2004 run at the U.S. Senate.

State Rep. Ron Stephens, R-Greenville, a pharmacist who is spearheading the effort to allow pharmacists to refuse to dispense the "morning-after" pill on religious grounds, said the poll results don't surprise him.

"That generally tracks with my understanding" of public opinion in Illinois, Stephens said. "I didn't determine my position on this based on what's popular.''

The poll also found that talk of a statewide ban on smoking in public places, another hotly debate issue in Springfield, is supported by fully two-thirds of the respondents.

"They tell you it's a 'no-smoking' section, but then you get the smoke coming at you from right across the aisle,'' said Don Walker of Carthage, who said he favors the ban. "I shouldn't have to put up with that."

kmcdermott@post-dispatch.com - 217-782-4912