'Obamacare Works,' Obama Tells Voters

President on campaign trail uses health care law.

DETROIT — -- Mired in low approval numbers, President Obama has shied away from campaigning for Democratic candidates before the midterms, but when he spoke at a rally this evening in Michigan, the president made a forceful case for his signature health law.

"I don't know if you've noticed, but Obamacare works," the president said.

Criticized by Republicans as an overreaching law that was rolled out ineptly, the Affordable Care Act eventually supplied health coverage to 8 million Americans who signed up for 2014 plans on Obamacare-created exchanges.

The law faces a critical test this month, as the 2015 open-enrollment period begins Nov. 15 for health plans on the exchanges.

Obama urged Michiganders to vote for Democratic Senate candidate Gary Peters and gubernatorial candidate Mark Schauer, telling an energetic crowd that Republicans aren't on their side.

"They don't have an agenda for the middle class. They don't have an agenda for Detroit. They don't have an agenda for Michigan," Obama said.

Before Saturday, Obama had visited Maryland to campaign for gubernatorial candidate Anthony Brown, Illinois for Gov. Pat Quinn, Wisconsin for gubernatorial candidate Mary Burke, Maine for gubernatorial candidate Mike Michaud.

He is scheduled to head back out on the trail Sunday in Connecticut.

Saturday's appearance was Obama's first with a Democratic Senate candidate.