A new poll by a respected Illinois think-tank shows Donald Trump with a big lead over his Republican challengers heading into that state’s March 15 primaries.

It’s a startling finding for a state that tends to embrace mainstream Republicans over radical ones — and one that has correctly called the winner of every GOP primary race of the past 60 years.

The poll, by the Paul Simon Public Policy Institute at SIU, shows Trump leading among six candidates, with 28 percent support, well ahead of Ted Cruz (15 percent), Marco Rubio (14 percent) and John Kasich (13 percent).

The poll was conducted in the week before Saturday’s South Carolina GOP primary and Nevada’s Democratic caucuses, and before Florida Gov. Jeb Bush withdrew from the race. Bush and Ben Carson both finished in single digits in the poll.

“A part of me is surprised that Donald Trump leads significantly in a state known for its moderate Republicans, from Everett Dirksen to Jim Edgar to Mark Kirk,” Charlie Leonard, a political scientist who helped supervise the poll, said in a prepared statement. “On the other hand, the ‘not-Trump’ vote, combined together, swamps the pro-Trump vote, with somewhere around one in seven voters still up for grabs.”

Most ominous for the GOP establishment is that, when it comes to Republican presidential primaries, Illinois has a long history of accurate prognostication. In fact, the last time Illinois Republican primary voters picked a candidate who didn’t go on to win the GOP presidential nomination was 1952, when they picked Robert Taft instead of Dwight Eisenhower.

David Yepsen, director of the Simon Institute, said there are two ways to look at the Republican race — as Trump being ahead because he has more votes than anyone else, or as Trump not being the first choice of 72 percent of polled Republican voters. He said if those 72 percent were to rally around another candidate, Trump would lose in Illinois.

The question now, he said, is who the alternative to Trump might be.

“As long as the non-Trump vote is divided, I think Donald Trump has every reason to think he’ll do well here,” Yepsen said Monday. 

MORE: Political pundits talk 2016 presidential election candidates

A parallel poll of Illinois Democrats found that Hillary Clinton, an Illinois native, held a commanding lead over Bernie Sanders, 51 percent to 32 percent, with 16 percent undecided.

The two telephone polls sampled 422 Illinois Democrats and 306 Republicans, and had margins of error of 4.7 percent and 5.6 percent, respectively.

Yepsen said this doesn’t guarantee Clinton a victory because the primaries are still three weeks away. He said it’s important to watch were supporters of former Bush, who dropped out of the race this week, go.

To be a contender against Clinton, Yepsen said Sanders must expand his voting base — like he is attempting to do with African-Americans in South Carolina — and get his supporters to the booths. 

“Younger Americans seem to like Sanders, but there’s not enough of them to guarantee his nomination,” Yepsen said.

He said this race is also likely to affect which way the Supreme Court leans, seeing as the new president is likely to name the Supreme Court justice who will take the place of Justice Antonin Scalia, who died Feb. 13.

MORE: Analysis: Election could ride on empty Supreme Court seat | Supreme Court battle renews focus on other nominations

He said it is also a big election in terms of issues in Illinois, especially because of the state’s historic budget stalemate, which has caused financial problems for colleges and universities. 

“We look at higher education spending issues — those are questions that are all going to be decided by politicians in Springfield,” Yepsen said.

The Daily Egyptian’s Anna Spoerre contributed to this report. 

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