CHICAGO – Chicago Teachers Union president Karen Lewis was hospitalized over the weekend, citing “discomfort.”

Lewis is contemplating a run for mayor and polling indicates she’s the biggest threat to incumbent Rahm Emanuel.

MORE NEWS: Know These Before Moving From Cyprus To The UK

The union denied a rumor she had suffered a stroke.

CTU spokeswoman Stephanie Gadlin added Lewis would decide ” whether or not another public statement is warranted.”

The Chicago Tribune notes “she underwent weight-loss surgery in Mexico in the spring.”

Gadlin added Lewis is resting well, in good spirits and is “thinking of creative ways to secure the future and city our students and their families deserve,” the Daily Herald reports.

A recent poll found in a head-to-head matchup, Lewis had 43 percent backing to 39 percent for Emanuel, with 14 percent undecided. It was a poll of 800 registered voters, according to the Tribune.

Lewis recently gave her campaign $40,000 and just received a $30,000 donation from the American Federation of Teachers. The AFT is the second largest teachers union in the country and Lewis is a member of the executive committee. The union has promised $1 million to defeat the incumbent mayor.

MORE NEWS: How to prepare for face-to-face classes

Emanuel reportedly has more than $8 million.

Lewis has not set a deadline for declaring her candidacy.