When President Barack Obama stormed to victory in 2008, you didn't have to look any farther than Chicago's suburbs to see how dominant his win was.
Suburban counties that had been solidly red for years -- reliably voting for Republican presidents in nearly every election -- all turned blue, delivering a substantial win for Obama in his home state.
Obama's popularity trickled down the ballot to help fellow Democrats Bill Foster and Melissa Bean to victory in Congress and deliver unprecedented numbers of suburban Democrats to Springfield, bolstering the party's majority in the General Assembly.
Four years later, after a grinding recession and a 2010 Republican resurgence that overturned control of the U.S. House, Illinois' delegates to this week's Democratic National Convention doubt Obama will have it so easy again.
In a Daily Herald survey, 71 percent of Illinois Democratic delegates who responded thought Obama could fall short in at least some suburban areas. Twenty-nine percent said the president can sweep the collar counties once again.
More than 91 percent expect an overall Obama victory on Nov. 6, with 7 percent calling his chances 50-50 and 2 percent saying it's an uphill battle. Fifty-one Democrats responded to the survey out of 214 total delegates.
As Obama and delegates begin to gather in Charlotte, N.C., for the convention opening Tuesday, the suburbs could be Illinois' version of a swing state -- an area where neither political party is assured a victory.
"They've underestimated (Obama) every time he's run," said state Sen. Terry Link, a Waukegan Democrat and Obama convention delegate.
Republicans have a big stake in winning the suburbs as well. Even though polls suggest former Massachusetts Gov. Mitt Romney is unlikely to win Illinois, riding his coattails in the suburbs could help Republican congressional representatives keep seats that are hotly pursued by strong Democratic challengers.
The GOP hopes it can return the collar counties to their Republican roots with the argument that a struggling economy and years of congressional gridlock have tarnished Obama's shine.
"I think you're going to see a different election in Illinois," said Illinois House Republican Leader Tom Cross of Oswego, whose home of Kendall County went for Obama in 2008.
"I don't think you'll see the type of results in the suburbs and downstate that we saw that time," Cross said.
In 2008, Obama won the Democratic stronghold of Cook County easily, but also carried DuPage, Kane, Lake, McHenry and Will counties.
In both 2000 and 2004, all of the collar counties voted for Republican President George W. Bush. And in 1996, for the re-election of popular Democratic President Bill Clinton, DuPage, Kane and McHenry counties went for his Republican opponent, Sen. Bob Dole. Lake and Will counties went for Clinton -- Lake by just 166 votes.
Republican nominee Mitt Romney's strength in Illinois in this year's primary campaign was the suburbs, a region that swept him to victory over fellow hopeful Rick Santorum, even though Santorum lived briefly in Lake County and attended Carmel Catholic High School in Mundelein.
Last month, Romney stopped in Elk Grove Village, perhaps showing his campaign won't give up on Illinois.
Roosevelt University political scientist Paul Green called Romney a "suburban candidate," adding "traditional Republican voters will come back to the party."
Others don't think it will be that simple.
John Jackson, a professor with the Paul Simon Public Policy Institute at Southern Illinois University, says the Romney and Paul Ryan ticket could be perceived as too conservative by moderate suburban voters, maybe giving Obama an edge.
Jackson points to 2010, when GOP nominee for governor Bill Brady won in the suburbs, but too narrowly to add up to a state victory -- even in a big year for Republicans -- partly because of his conservative social positions.
"That puts (Romney and Ryan) somewhat in the position of Bill Brady in the governor's race," Jackson said.
What's been clear in recent elections is that the suburbs aren't the Republican lock they once were.
How Obama does in the suburbs could trickle down to candidates for Congress -- an idea not lost on the local party faithful on both sides.
Even as counties have tended to vote for Republican presidents, they also put into office former Democratic congressional Reps. Melissa Bean of Barrington and Bill Foster of Naperville. Both Foster and Bean lost in the 2010 Republican wave election, but Democrats have legitimate shots to win the seats back in 2012. Foster is taking another shot this year against Republican U.S. Rep. Judy Biggert of Hinsdale in the 11th District in DuPage and Will counties.
The fates of other candidates could swing one way or the other, depending on how Obama does. Democrat Brad Schneider of Deerfield is challenging U.S. Rep Robert Dold of Kenilworth in the 10th District in Lake and northern Cook counties, and Democrat Tammy Duckworth of Hoffman Estates is taking on U.S. Rep. Joe Walsh of McHenry in the 8th District in northwestern Cook, central DuPage and eastern Kane counties -- two seats national Democrats have identified as key to their battle to retake the U.S. House.
While Illinois' Democratic delegates will cheer their home state candidate this week, they'll also know that as Obama goes, so they may go.
"In 2008, he was able to excite segments of the population that would generally never vote or support a Democratic candidate," Obama delegate Moises Garcia of West Chicago said. "Although I don't believe the same excitement is there, I think he will be able to carry some of these counties in the upcoming election."