SPRINGFIELD — Time is ticking down for Illinoisans to make up their minds.

With Election Day looming on Tuesday, polling numbers and informal surveys project close races for President Barack Obama’s old U.S. Senate seat and the governor’s mansion.

But it remains unclear if the anti-incumbent mood of the nation will translate into higher voter turnout in Illinois, which has 7.4 million registered voters.

In 2006, the last election in which both a governor and a U.S. senator were being elected, turnout was 48.6 percent. In 2002, turnout statewide was 51.8 percent.

Experts are predicting a lower number.

“I’d be surprised if it clears 50 percent,” said political scientist Brian Gaines of the University of Illinois Institute for Government and Public Affairs. “I think we’re talking more like 47 or 48 percent.”

Several factors may play into the low figure. For Democrats and independents, there may not be as much excitement about going to the polls to vote for the home-state candidate for president, Barack Obama. Similarly, analysts say students are not as excited about the candidates.

In the February 2010 primary, which catapulted state Sen. Bill Brady of Bloomington into the general election race against Democrat Pat Quinn, vote totals show record-low turnout, despite a super-heated political climate.

The 23 percent turnout in February broke the previous record low of 25 percent in 1978 and 2006 Illinois State Board of Elections officials are predicting turnout levels to be similar to recent gubernatorial election years.

“Voter turnout in the last six contests for governor has been stable,” Executive Director Dan White said.

As the long and expensive 2010 campaign season entered its final hours, the candidates were barnstorming across the state in an attempt to snatch up any wavering voters.

Quinn sought to get a bounce from a third and final visit to Illinois from Obama.

Brady was planning to join U.S. Senate candidate Mark Kirk at a rally in Chicago featuring U.S. Sen. Scott Brown, who won the Massachusetts Senate seat held by the late Edward Kennedy.

The Illinois Republican Party launched an 11th-hour “social media” push to reach potential voters via e-mail, Facebook, Twitter and the party’s iPhone app.

“We’re reaching out to voters in unprecedented ways, and our efforts will be critical in tight legislative contests,” party Chairman Pat Brady said.

Gaines said both parties tend to overstate the effect of their voter mobilization efforts in an attempt to generate excitement among voters in the closing days of a campaign.

“I tend to discount that,” Gaines said.

Brady and Quinn were trying to keep voters from straying over to independent Scott Lee Cohen or Green Party candidate Rich Whitney, both of whom were polling in the single digits.

Brady has raked in big dollars from the Republican Governor’s Association and is en route to outspending Quinn, casting him as a bumbler who wants to raise taxes in a series of television ads that have been running since the summer months.

Quinn has been buoyed by labor unions, which support his tax increase proposal. He has portrayed Brady as a conservative with extreme views on such hot button issues as abortion and gay rights.

The fight for the U.S. Senate seat between Kirk and Democrat Alexi Giannoulias has been marked by name-calling — “liar” and “mob banker,” for example — and heavy attention from Obama and top Republicans.

At stake could be control of the U.S. Senate.

Republicans are hoping to not only ride a national wave of anti-incumbent sentiment back into power, but they hope it ripples through down ballot races for the Illinois House and Senate.

The GOP is hoping to bite a chunk out of the Democratic majority in the state Senate by dumping incumbents such as Deanna Demuzio of Carlinville, Mike Noland of Elgin and A.J. Wilhelmi of Joliet.

Senate Minority Leader Christine Radogno, R-Lemont, predicted Thursday that Republicans could pick up three to five seats in the Senate, leaving them in the minority but taking away the Democrat’s veto-proof majority.

Across the Rotunda, House Speaker Michael Madigan has pumped millions of dollars into defending his majority against Minority Leader Tom Cross’ attempt to win back a majority. Incumbents such as Mount Zion Democrat Bob Flider and Jay Hoffman of Collinsville have plugged up the airwaves with TV and radio ads hoping to stave off their opponents.

In the race to replace Giannoulias in the state treasurer’s office, Republican state Sen. Dan Rutherford of Chenoa is facing off against former state lawmaker Robin Kelly, D-Matteson.

If Rutherford and Brady win, it would be the first time in more than a decade that Illinoisans picked two downstate residents to serve in statewide office.

Republican Judy Baar Topinka, who served three terms as treasurer, is looking to make a political comeback as comptroller. She faces state Rep. David Miller, a Democrat from Lynwood.