Editor's note: John Avlon is a CNN contributor and senior political columnist for Newsweek and The Daily Beast. He is co-editor of the book "Deadline Artists: America's Greatest Newspaper Columns."
(CNN) -- The Illinois primary should be a Republican Party homecoming. After all, this is the Land of Lincoln, home state of the first Republican president.
But the party of Lincoln is no longer an easy fit for the state of Illinois. After serving as a Republican presidential stronghold from 1850 to 1920, as well as a more recent stretch from 1972 to 1988, Illinois is now the seventh most Democratic-leaning state in the nation, after the Northeast and Hawaii.
The swing districts of the Chicago suburbs increasingly lean Democrat.
And while nearly two-thirds of the state's population is clustered around Chicago, more than 50% of the Republican vote comes from "downstate," the more rural and conservative districts.
All this should make Illinois a strong state for Mitt Romney, and the polls show him in pole position heading into the primaries. But the erosion of the ranks of centrist Republicans in the state gives Romney a smaller base of support to draw upon, while Rick Santorum can look to tea partiers, evangelicals, the "very conservative" and voters making under $100,000 -- which have been his base to date.
And in the big picture, this will likely be the last day that Republicans pay attention to the Land of Lincoln in 2012, not just because President Obama was previously the state's senator.
With the notable exception of centrist Republican Sen. Mark Kirk, who is slowly recovering from a tragic stroke, the GOP seems to have almost given up on Illinois.
In the past, the Illinois GOP put forward a steady stream of competitive candidates, many of whom became national figures. Abraham Lincoln was the face of the founding of the Republican Party, rooted in a commitment to overturn the brutal institution of slavery. Ronald Reagan was born in Dixon, Illinois. The first African-American congressman elected in the 20th century, Oscar Stanton de Priest, represented the 1st District in Chicago.
Legendary Senate Minority Leader Everett Dirksen (with a voice once described as "like honey poured over gravel") helped shepherd through civil rights legislation while representing Illinois as a Republican.
Sen. Charles Percy helped define the center right in the 1960s. Future defense secretary Donald Rumsfeld was an Illinois congressman, as was John Anderson, who pursued a third party campaign in 1980. During the Reagan era, two Illinois GOPers, House Minority Leader Bob Michel and social conservative stalwart Henry Hyde helped define both wings of the GOP. And for what it's worth, the last twice-elected, non-indicted governor of Illinois was also a centrist Republican, the popular Jim Edgar.
Why recite this Illinois Republican laundry list? It shows the party was formidable in the Land of Lincoln back in the day when it had a strong centrist wing as well as an array of litmus-test conservatives. Now, hemmed in by a lack of real diversity in its ranks, the GOP struggles in part because it doesn't have strong support in the suburbs, let alone the cities.
Mitt Romney appeals to the state's center-right in this race, but it is largely because of his record as Massachusetts governor, not because of the stands he has taken in his presidential campaign.
Romney has also notably failed to inspire voters with the arguments he's put forward. As Michel recently said, "He's not overwhelming, that's the problem through the whole damn primary. What's the spark? What's the thing that gets him off and running? No one knows."
Outspending Santorum 7 to 1, Romney looks like he's in strong position for a win in the Land of Lincoln Tuesday night. But with low Republican registration in Chicago and the suburbs, Santorum and/or Gingrich could also outperform by rallying the more rural downstate to their side. It's time to set aside the polls and wait for the votes to be counted.
Regardless, it is sad that the party of Lincoln has all but abandoned the Land of Lincoln in general elections. It represents the retreat that comes from rejecting the progressive Republican tradition that dates back to Abraham Lincoln himself.
When the GOP starts to once again embrace and elevate its centrist leaders, Republicans can look forward to competing in the Land of Lincoln -- and every other "blue" state across the nation.
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The opinions expressed in this commentary are solely those of John Avlon.