U.S. Sen. Amy Klobuchar has an imposing lead over Republican challenger Jim Newberger, while U.S. Sen. Tina Smith holds a much smaller advantage over state Sen. Karin Housley in the special election race for Minnesota’s other U.S. Senate seat.

A new Star Tribune/MPR News Minnesota Poll found that Smith, appointed by DFL Gov. Mark Dayton after Al Franken resigned in January, leads Housley by 44 to 37 percent. But the contest could still be up for grabs: 15 percent of likely voters are undecided.

The poll’s most startling disparity was the difference in young voters’ preferences: 64 percent in the 18-34 age group said they would vote for Smith.

Just 16 percent of those voters backed Housley, who did best among voters ages 50-64 and older. Housley has made senior citizen issues a focal point of her campaign. Smith could be the beneficiary of a national Democratic effort to mobilize young voters.

State registration data released this month found a surge in new voters this year. Almost two-thirds of the newcomers were 18 to 30 years old.

See the full Minnesota Poll results.

How the poll was conducted Today’s Star Tribune/MPR News Minnesota Poll findings are based on interviews conducted Sept. 10-12 with 800 Minnesota likely voters. The interviews were conducted via landline (60 percent) and cellphone (40 percent). The poll was conducted for the Star Tribune and Minnesota Public Radio News by Mason-Dixon Polling and Research Inc. Results of a poll based on 800 interviews will vary by no more than 3.5 percentage points, plus or minus, from the overall population 95 times out of 100. Margins are larger for groups within the sample, such as Democrats and Republicans, and age groups. The self-identified party affiliation of the respondents is 37 percent Democrats, 31 percent Republicans and 32 percent independents or other. Sampling error does not take into account other sources of variation inherent in public opinion surveys, such as nonresponse, question wording or context effects. In addition, news events may have affected opinions during the period the poll was taken. Readers can e-mail questions to djmcgrath@startribune.com.

The telephone poll of 800 likely voters was conducted Sept. 10-12 and has an error margin of plus or minus 3.5 percentage points. Voters’ views of the two candidates reflected the intense partisanship evident in Minnesota and across the nation.

“I don’t like Tina Smith simply because she’s a Democrat and I think she’s going to mimic Dayton, and I don’t like him and I never have,” said Marvel Caouette, 83, a retiree who lives in Brainerd.

“For a newcomer, [Smith] is fitting right in. She seems to care about the people,” said B.J. Crigler, 69, a retiree from Saginaw. Crigler said she’ll vote for Democrats “even if I don’t like them” because she is so opposed to President Donald Trump and his policies.

Housley and, to a lesser extent, Smith remain unfamiliar to many Minnesota voters. Almost half of those polled didn’t recognize Housley’s name, and 26 percent said the same of Smith. Of those who did know of them, about one in four voters said their views of each were neutral.

Those results suggest an opening for both candidates to introduce themselves, try to shape opinions of their opponent and sway voters in the campaign’s final seven weeks.

Attacks are a typical campaign tactic for accomplishing that. The Smith campaign last week went after Housley for voting against state legislation that was meant to improve working conditions for women and for siding with special interests when she voted against a bill that imposed annual fees on pharmaceutical companies to address the opioid epidemic.

The Housley campaign released a campaign video titled “Hypocrite” that criticized Smith for supporting U.S. Rep. Keith Ellison’s DFL campaign for state attorney general after he was accused of domestic abuse. Republicans also have questioned an offshore investment held by Smith’s husband.

Minnesota last elected a Republican senator in 2002, and this race is a priority for national political parties as the GOP fights to protect its slim 51-49 edge in the U.S. Senate.

The stakes are reflected in campaign cash: As of the end of July, Smith had raised $4.8 million and Housley had collected $1.8 million. Smith fended off a primary challenge from Republican-turned-Democrat Richard Painter in August.

The winner will finish Franken’s original term, and the seat will be on the ballot again in 2020.

Smith’s support is strongest in Hennepin and Ramsey counties, traditional DFL bulwarks, and in southern Minnesota, where her work on the Farm Bill and attention to expanding broadband access could be paying off.

Housley fared better than her opponent in northern Minnesota and the other Twin Cities metro counties.

Cultivating those suburban voters could be key to Housley’s chances. Suburbs’ Republican tilt was clear here and across the U.S. in 2016, when Anoka, Carver and Scott counties backed Trump. But some national polls have recently tracked declining support for the president and GOP candidates among suburban voters.

National polls show a gender gap — with a growing number of women disapproving of Trump’s performance — that’s also evident in the Smith-Housley race. Almost half of women said they support the Democratic senator; 43 percent of men backed Housley. Fifteen percent of men and women said they’re undecided.

Jerry Trooien, an unaffiliated candidate in the Housley-Smith race, and Sarah Wellington, the Legal Marijuana Now candidate, each got support from 2 percent of respondents.

The poll found that health care is the top concern for voters in both U.S. Senate races, followed by the economy and jobs. Immigration was third.

“Health care is the big one for my family,” said Kelly Martinson, 46, a freelance writer from St. Paul. Klobuchar’s support for the Affordable Care Act is a reason she supports the senator. Before it took effect, Martinson said, her family paid thousands of dollars for coverage.

For Jerold Ford, 55, who lives in Amor Township near Battle Lake, candidates’ stances on taxes are key — and the reason he’ll vote for Republicans. Democrats, he said, “just want taxpayers’ money.”

Six years ago, Klobuchar beat state Rep. Kurt Bills by almost 1 million votes, a margin of 65 to 30 percent. The poll suggested that another landslide could be taking shape in her current campaign against Newberger, a Republican state representative.

Klobuchar has the backing of 60 percent of likely voters; Newberger had 30 percent and just 6 percent were undecided. Legalize Marijuana Now candidate Dennis Schuller had 3 percent and the Green Party’s Paula Overby had 1 percent.

Klobuchar was ahead across demographic groups — leading Newberger among women, men and voters of all ages and income ranges — and in every part of the state. Her support was strongest in Hennepin and Ramsey counties, where 69 percent said they’ll vote for her. Newberger’s only advantage was among Republicans.

Caouette’s take on his campaign summed up Newberger’s obstacles. “I don’t know anything about him,” she said.

“Klobuchar has done some good things, so I don’t know. When I vote, I vote for who I think will be the best for Minnesota,” said the longtime Republican. “I need to know her opponent, and I just don’t.”

Speculation about whether Klobuchar might run for president in 2020 has been fueled by her rising profile. She’s an outspoken Trump critic who appears regularly on cable TV news shows and this month posed tough questions to Judge Brett Kavanaugh, Trump’s U.S. Supreme Court nominee, from her perch on the Judiciary Committee.