The race to defeat one of the most powerful Democrats in the nation is narrowing — with incumbent U.S. Sen. Dick Durbin just seven percentage points ahead of Republican challenger Jim Oberweis, according to a new Early & Often Poll.

In a year that’s expected to tilt toward Republicans across the nation, Durbin, the No. 2 Democrat in the U.S. Senate, is leading Oberweis, who is making his third run for the Senate, 47.8 percent to 40.5 percent, the survey commissioned by the Sun-Times’ political portal shows. 

And in the first major survey since an Illinois State Board of Elections ruling allowed the Libertarian Party onto the ballot, candidate Sharon Hansen had a showing of about 4 percent.

Another 7.6 percent of those queried said they were undecided in a race that has for the most part fallen under the radar screen, compared to the kind of attention the contest for Illinois governor has garnered. 

The automated poll of 1,054 people was conducted by We Ask America on Aug. 27.

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Given the poll’s margin of error of plus or minus 3.02 percentage points, the U.S. Senate race could be even tighter. A Rasmussen poll conducted in April had Durbin leading by 14 points. But a CBS News/NYT/YouGov Internet poll taken in July had Durbin with an 8-point lead.

The closesness of the contest may lie in the two candidates’ vulnerabilities.

One of Durbin’s biggest weaknesses? The amount of time he’s spent in Washington.

Of those surveyed, 60 percent responded they were less likely to vote for a U.S. Senate candidate who had served in Washington, in the Senate and Congress, for 31 years. However, 39 percent said they were either more likely to vote for such a candidate or that it made no difference. 

It’s an issue that Oberweis has hit on repeatedly in the campaign.  The Republican regularly adds “career politician” before Durbin’s name and routinely works Durbin’s years in office into his attacks.

Oberweis has his own vulnerability: the number of times he’s run for office. 

Respondents did not warm to the idea of a perennial candidate. 

More than half, 54 percent of those asked, said they were less likely vote for someone who has repeatedly run for office. 

Still, when asked: “If a candidate for the U.S. Senate has run five unsuccessful campaigns for various public offices in the past, would that make you more likely or less likely to vote for him?” 44 percent said they were either more likely to support that person or that it made no difference.

POLL DETAILS: The Early & Often Poll is based on a random sample of 1,054 likely Illinois voters in the Nov. 4 election. It is an automated poll conducted by We Ask America. Respondents were contacted by telephone on Wednesday, August 27, 2014. About 23 percent were reached on their cellphones. The survey has a margin of error of plus or minus 3.02 percentage points, larger for demographic subgroups.

Oberweis, a Sugar Grove Republican, had run unsuccessfully five times for U.S. Senate, governor and Congress before he was elected in 2012 to the Illinois Senate. The magnate of Oberweis Dairy has touted his business experience and railed against high taxes and Durbin’s deep ties to Washington.

The poll also explored immigration, an issue dear to Durbin, who was among the “gang of eight” to broker a landmark, bipartisan U.S. Senate immigration deal. The measure ultimately failed to gain traction in the U.S. House. Durbin was also the original sponsor of the Dream Act, which would allow for the children of illegal immigrants to get an education in the United States without fear of deportation. 

By contrast, Oberweis has suffered for years to overcome a once debilitating TV ad in which he’s pictured in a helicopter hovering over Soldier Field as he criticizes illegal immigrants. In April, Oberweis apologized for his past remarks on the issue. 

“Early on, I spoke up forcibly on the need to secure our borders and bring immigration into this country under the rule of law,” Oberweis said. “I regret the harsh tone of my rhetoric 10 years ago. But my principles remain intact.”

Durbin has sought to make Oberweis’ past an issue. When Oberweis first talked of running again last year, Durbin said Hispanics “who will never get over that ad” had already begun contacting his office.

“They felt it was hateful and divisive, and they’ve called to say they’re anxious to help and to make sure that he doesn’t get elected,” Durbin told the Sun-Times last November.

Still, the poll showed only a five percentage point spread between those identifying with Durbin and those with Oberweis on immigration reform. Another 26 percent said they were unsure of which candidate best represented their view on the issue.

Overall, the poll found a bit of a gender gap.

Durbin was leading Oberweis, 49 percent to nearly 37 percent among women. Men were more evenly split: 45 percent for Durbin and nearly 47 percent for Oberweis.

Not surprisingly, Durbin and Oberweis enjoyed their strongest support among voters who identify with their respective parties. Independent voters were more evenly split, with 41 percent choosing Durbin, and nearly 44 percent selecting Oberweis. Libertarian Hansen enjoyed her strongest support among independents, picking up nearly 8 percent.

Durbin was beating Oberweis in Chicago and suburban Cook County. Oberweis was leading in the collar counties, while Downstate voters were more evenly divided.

The Durbin campaign dismissed the survey numbers, saying internal polling showed the state’s senior senator led his opponent by double digits despite a “barrage” of negative ads against Durbin. 

“In a lot of ways I think that [state] Sen. Oberweis has been as aggressive as he can be,” Durbin spokesman Ron Holmes said, referencing, among other things: “Giving out free ice cream for votes on the South Side … Clearly Sen. Oberweis’ radical tea party agenda still finds him significantly behind in the polls, despite a million dollars in right-wing SuperPAC spending and a barrage of negative and false attack ads.” 

Holmes was referencing Americas PAC, which has funded radio ads attacking Durbin. 

“The question is what will be his next big lie?” Holmes said, accusing Oberweis’ campaign of concocting an issue of pay inequity “an IRS conspiracy, asking us to return donations from the Bush era. There is a string of mistruths that Dan Curry and the Jim Oberweis campaign are painting. The facts just don’t add up.” 

Oberweis campaign spokesman Dan Curry, however, called the numbers indicative of a fed-up electorate.

“Career politicians like Dick Durbin are starting to drown in the backwash of their failed policies. The public is tired of excuses and blame shifting,” Curry responded in a statement. “They want more jobs, a better economy, better schools and safer neighborhoods — not what they are getting from Dick Durbin.”

Pollster Gregg Durham said the seven-point spread is indicative of something else.

“The tight numbers may be a reflection of a Republican year,” he said. “Still, Sen. Durbin is close to 50 percent in the poll. He has the advantage of a large campaign fund and an experienced campaign staff. That can’t be ignored.”

Durham said a candidate’s true show of strength is when he or she reaches more than 50 percent in the polls. 

“That’s when you reach the basically the finish line,” Durham said. Then, referring to Durbin, he added: “He’s close to that.”

Contributing: Sydney Lawson