"Agree or disagree with Marco Rubio on various issues, he offers Illinois voters the framework of a presidency that realistically could exist," the paper's editorial board wrote
But it had less praise for Illinois native Hillary Clinton and her Democratic rival Vermont Sen. Bernie Sanders.
"Our custom is to offer primary election endorsements to candidates of both major parties. But the 2016 race confronts Illinois voters with uncommon dangers, because so many candidates are playing with fire," the editorial said.
The Illinois Republican and Democratic primaries are Tuesday.
The editorial board wrote that Rubio's foreign policy experience greatly exceeds his opponents' and praised his policies on spending limits and balancing the budget.
"No candidate in this cycle has ridden more ups and downs than Marco Rubio," the paper wrote.
"We like his youth, his bilingual fluency and the fact that he isn't one more Republican who's been standing in line, awaiting his turn to run," the board added.
The paper found the Democrats' policies problematic, arguing they propose no plans that would curb federal spending.
"Hillary Clinton and Bernie Sanders have not met this fundamental economic test. We're keeping an open mind, hoping that whichever of them prevails will meet that test in the general election campaign," the board wrote.
"Given the distance from economic reality that Clinton and Sanders have catapulted in their exhortations, we cannot endorse either of them in the Illinois primary election," the paper wrote wrote.
CNN has reached out to the Sanders and Clinton campaigns for comment.