State Senate candidates in the Worcester-Middlesex District spent the first day of the workweek pounding pavement, hoping to turn out the most votes in the special election Tuesday.

While campaign signs dot front lawns across the district, Paul Weizer, a professor of political science at Fitchburg State University, forecasts low voter turnout.

“In a special election where its really going to be a fraction of the electorate that pays attention and turns out, anything could happen,” he said.

Weizer expects well under 20 percent of registered voters will cast ballots Tuesday, when four candidates are on the ticket.

He said turnout will be low because the election falls on a date people don’t normally associate with voting. People are already into the holiday mindset, and the state Senate race is the sole vote on the ballot.

That means Tuesday’s voters won’t be fair-weather supporters, said Weizer. They’ll be committed to their candidate.

“Really it comes down to who gets their people out to vote,” he said.

Democrat Sue Chalifoux Zephir has appeared with several high-profile Democrats, including members of the US Congressional delegation Elizabeth Warren and Ed Markey, during the campaign.

During a break from knocking on doors, the Leominster city councilor said in a telephone interview that voters must decide between four candidates with “serious differences” on policy, highlighting her stance as a pro-choice candidate who supports a $15 minimum wage.

She said the election is important because the person who is elected will sworn in to vote on a host of critical issues affecting the state. Her campaign, she said, is working overtime to ensure she gets the most of votes.

“We are not taking one vote for granted, we are going after every single vote because in a three way race every vote matters,” she said.

Republican candidate and Fitchburg City Councilor Dean Tran spent his final daylight pre-election hours campaigning in Westminster, a town split almost evenly in terms of registered Republican and Democratic voters.

“It’s just a normal day,” said Tran in a telephone interview.

Tran, who was endorsed by Gov. Charlie Baker and Worcester County Sheriff Lewis Evangelidis, said he is approaching the general election with a sense of fatigued positivity.

“I haven’t had any time to think about how I feel but I think I feel confident, and excited at the same time. Tired and glad that the election day is here,” he said.

Claire Freda, the unenrolled candidate, spent a few hours on Monday handing out free meals at an annual luncheon at Il Forno in Fitchburg.

Her campaign volunteers knocked on district doors Monday, and Freda said she’ll attempt to travel to all 11 district communities today.

Freda said she has a “good feeling” about the election. Her decision to delay campaigning until after the Democratic field was narrowed in the Nov. 7 primary paid off, she said.

She said her gold-and-blue signs can now be seen throughout Leominster, where she serves as a city councilor, and beyond.

“It turned out to be a great advantage, our camp is energized and we have a lot of visibility,” she said.

Green-Rainbow Party candidate Charlene DiCalogero campaigned Monday in Berlin and Lancaster, where she said voters who learned of her candidacy responded positively to her decision to refuse campaign donations over $250.

“That there is someone new to them who is running who has spoken clearly about being the only candidate to refuse all corporate lobbyist money,” the Berlin library trustee said.

Her campaign did not have funds to send “shiny glossy mailings” to voters, said DiCalogero. She’s focused on meeting voters face-to-face, she said.

DiCalogero said her mission is to show Worcester-Middlesex residents they have options this special election.

“The most important message I’ve been trying to get to the people in the 11 cities and towns is yes, you do have real choices this year, and I am the only candidate who is listening to the people, and not the companies,” she said.

Whoever wins Tuesday’s election will serve out the remainder of former state Senator Jennifer Flanagan’s term. They’ll follow an accomplished state Senator, said Weizer.

“Any seat in the senate with only 40 seats is significant, we’ve had a very strong senator for a number of years,” he said. “Clearly whoever replaces her has big shoes to fill.”

The district encompasses Fitchburg, Gardner, Leominster, Berlin, Bolton, two precincts in Clinton, Lancaster, Lunenburg, Sterling, Wesminster and Townsend.