(The following is an analysis from A.J. Simmons, UIS Center for State Policy and Leadership Research Director, and Assistant Director Nicholas Waterbury.)
In 2026, for the first time in 30 years, Dick Durbin will not appear on the ballot for Illinois’ Class II U.S. Senate seat. With his retirement, the race is wide open, and both major political parties are vying to field competitive candidates.
On the Democratic side, the contest has largely centered on three familiar names: Lieutenant Governor Juliana Stratton, U.S. House Representative Robin Kelly, and U.S. House Representative Raja Krishnamoorthi. On the Republican side, the contenders include former state Republican Party chair Don Tracy, attorney Jeannie Evans, businessman Casey Chlebek, and others.
As the primary elections approach this month, we took a closer look at what the data can and cannot tell us about where things stand. Different indicators may point in different directions. And one of the most powerful predictors of electoral success, incumbent advantage, does not apply here.
What do the polls show?
Public polling in the Democratic primary has varied in the exact percentages, but not in the basic storyline. In many publicly released polls, Krishnamoorthi has led the field. Looking at polls conducted within six months of the primary, he registers between 29% and 43% of voter support. But importantly, recent polls have shown noticeable momentum for Stratton, even overtaking Krishnamoorthi in at least one recent survey.
Still, 15% to 30% of polled voters in the past few weeks remain undecided. That is a sizable bloc, especially this close to Election Day, and it leaves room for movement, especially with Stratton seemingly improving her standing in recent polls.
On the Republican side, only one public poll has been released. In January of this year, an incredible 84% of primary voters were undecided, a striking figure two months from an election.
Following the money
Fundraising is often treated as a measure of candidate strength. By that metric, Krishnamoorthi holds a commanding lead. According to the most recent FEC filings, he has raised about $30 million. Stratton has raised approximately $4 million, and Kelly about $3.3 million. These totals will likely increase in additional FEC filings. Further, Illinois Governor J.B. Pritzker has donated $5 million to a PAC supporting Stratton. That money could prove significant in the closing stretch.
Republican totals are modest compared to the Democratic primary. Fundraising numbers show Tracy leading with about $2.1 million raised. Evans has raised just over $500,000, and Chlebek about $100,000 in the most recent disclosures available online.
Endorsements
Endorsements are another commonly cited signal of candidate strength. Here, the picture is more muddled. All three Democratic candidates report similar endorsement totals and boast supporters from state and federal politics. No single campaign appears to dominate this metric, and all campaigns have brought in big names from out of state in the closing weeks. That’s not true on the Republican side, where endorsements tilt clearly toward Tracy.
The State of the Race
In summary, the Democratic race has mixed indicators of who is in the lead, with some indicators pointing towards Krishnamoorthi but with a potentially late-surging Stratton, while the Republican race has a frontrunner in traditional measures but without polling to back him up. In a race like this, we turn to a less-common approach to gauging the race.
What do voters think will happen?
Rather than relying only on traditional indicators like “who are you going to vote for” questions, we asked voters a different question.
Who do you think is going to win?
Political scientists call this a voter forecast. Our previous research in Illinois found that voters were remarkably accurate in predicting J.B. Pritzker’s win and the vote margin in the 2022 gubernatorial race. In-progress research of ours on the 2024 presidential election suggests that voters performed well when predicting who will win their state or the national election, and even the national popular vote. They were less accurate when forecasting the Electoral College breakdown, suggesting there are limits on what voters can forecast accurately.
But primaries are different than general elections. They receive less media attention and often engage fewer voters. That may mean less information for people to draw on when making predictions. It is an open question how accurate voters will be in less publicized elections.
Our survey findings
As part of a larger academic survey of registered Illinois voters fielded in late fall, we asked those partisans and independents intending to vote in the Democratic primary, whether they identified as a Democrat or an independent, who they believed would win the nomination. Among the voters, 35% predicted Krishnamoorthi would win, 17% chose Stratton, and 13% chose Kelly. Still, a staggering 35% were unsure or thought someone else besides the three most prominent candidates would prevail.
Table 1: Voter Forecast of the Democratic Senate Primary
| Early March 26 | Late Fall 25 | |
| Juliana Stratton | 20% | 17% |
| Raja Krishnamoorthi | 46% | 35% |
| Robin Kelly | 16% | 13% |
| Someone else/Not sure | 18% | 35% |
We asked the same question again over a two-week period running from the end of February to last week. The share of likely Democratic primary voters predicting a Krishnamoorthi victory rose to 46%. Stratton ticked up to 20% as did Kelly at 16%. Meanwhile, the unsure or someone else category dropped to 18%.
Overall then, as the primary nears, voters appear more confident in their expectations and increasingly think Krishnamoorthi will be the likely nominee, but there is no widespread consensus.
Illinois primaries allow any registered voter to participate regardless of partisan affiliation, and this leads to voters with varying attachments to the political parties weighing in on who the party nominates, including independents. When we look at differences between self-professed “strong” Democrats and “weak” Democrats, we see that they are even more certain in Krishnamoorthi’s status, with 56% predicting him as the winner.
“Strong” Democrats are the most likely to vote in the primary, and, in general, are the most confident in their predictions for the primary.
Table 2: Forecast of the Democratic Senate Primary By Partisan Intensity
| Strong Democrats | “Weak” Democrats | |
| Juliana Stratton | 21% | 20% |
| Raja Krishnamoorthi | 56% | 50% |
| Robin Kelly | 16% | 15% |
| Someone else/Not sure | 7% | 14% |
Compared to Democrats, Republican primary voters, which like with the Democrats includes partisans and independents, appear more uncertain about the outcome of their primary.
On the Republican side, we did not include a forecast question in the autumn survey, as the field was unsettled and awaiting potentially more well-known candidates. But in our recent wave, 28% of all likely Republican primary voters predicted Don Tracy would win. Jeannie Evans followed at 21%, Chlebek at 14%, and a staggering 37% remaining unsure or predicting someone not listed.
Table 3: Voter Forecast of the Republican Senate Primary
| All Rep. Primary Voters | Strong Republicans | Weak Republicans | |
| Don Tracy | 28% | 35% | 32% |
| Jeannie Evans | 21% | 24% | 22% |
| Casey Chlebek | 14% | 20% | 16% |
| Someone else/Not sure | 37% | 20% | 29% |
As with the Democrats, “strong” Republicans are even more certain in the favorite over “weak” Republicans and all Republican primary voters, with Tracy seeing a seven-point increase among that group compared to all voters in the survey. Evans remains second and Chlebek third. We see the “unsure/someone else” category drop in half amongst “strong” Republicans, though it remains a potentially impactful amount.
A final wrinkle: voters are still undecided
Perhaps the most striking finding is this: Many primary voters just are not sure which candidate is likely to prevail.
Less than three weeks before the election, 18% of likely Democratic primary voters and 37% of likely Republican primary voters said they had not yet chosen a candidate they thought would win. Among Democrats, that figure closely mirrors public polling of voter preferences.
Among Republicans, limited polling makes comparisons harder, but the high uncertainty is notable. Further, our sample is not of all registered voters. They are voters who say they plan to participate in the primary, including partisans and independents. That suggests many decisions may be made late in the race, which could influence assessments of the outcome.
If voters themselves are still deciding, forecasting the outcome becomes more complicated. Plus, voters who at the time of fielding thought they’d vote in the primary may not, and some registered voters who weren’t going to vote in the primary may change their mind to do so.
So, how will they do?
With just days to go, will voters accurately predict the winners of their respective primaries?
In full transparency, we do not know. This is, for us, an ongoing experiment.
On one hand, forecasting primary outcomes may prove more difficult than predicting general elections, where information is more abundant and engagement higher.
On the other hand, citizen forecasts have been successful in predicting a diverse range of outcomes, including low information situations.
Soon, we will find out. In the meantime, let us know in the comments who you think will win the Democratic and Republican senate primaries.
(This analysis from A.J. Simmons, UIS Center for State Policy and Leadership Research Director, and Assistant Director Nicholas Waterbury.)
