WASHINGTON — A majority of Americans oppose letting employers, based on their religious views, exclude certain contraceptives from workers' insurance coverage, says a Reuters/Ipsos opinion poll ahead of a U.S. Supreme Court decision expected on Monday.

In one of the most closely watched cases of the year, the nine-member court will weigh whether for-profit corporations may raise religious objections to a mandate in President Barack Obama's signature 2010 healthcare law that their insurance cover contraceptives.

It brings to the forefront thorny questions of religious freedom and reproductive rights, along with enduring politicking over the law known as Obamacare, itself broadly upheld by the Supreme Court in 2012.