CHICAGO - Illinois might seem the least likely place for the health care law to get sidelined. It’s a state with a Democratic governor and solid Democratic majorities in both houses of the Legislature. It’s also the political base of President Obama, who championed the legislation in the face of furious opposition.

Yet even here, voters are divided on the law’s merits, and a bill authorizing creation of a state-based health insurance exchange - a centerpiece of the law designed to expand coverage to millions of people - has been stalled while state lawmakers wait to see how the court rules.

With the legislative session recently ended, some speculate Quinn will act unilaterally to set up the exchange by issuing an executive order - the approach taken by governors in New York and Rhode Island.

Creating the exchanges has been “a hard sell’’ in many states, even those that appear politically receptive, said Thomas Miller, a resident fellow at the American Enterprise Institute.

Seventeen states have put implementation on hold until the court’s decision, according to the Center on Budget and Policy Priorities. An additional 13, plus the District of Columbia, have authorized their creation.

The exchanges are supposed to function as online marketplaces where consumers can compare health plans and determine their eligibility for programs such as Medicaid or subsidies to help buy coverage.

States must submit their blueprints by Nov. 16 and get conditional approval for their plans no later than January 2013 to begin enrolling residents 10 months later.