By Lesley Clark, McClatchy Washington Bureau (TNS)

WASHINGTON — On the campaign trail, Hillary Clinton and Bernie Sanders shy away from direct mentions of each other, focusing instead on the Republicans.

But when the two top-polling candidates for the 2016 Democratic presidential nomination face off for the first time Tuesday in the first Democratic debate, it will be hard to escape the fact that they have had very different approaches to major issues from war to paychecks.

Here’s a preview of the areas where they differ.

Super PACs

Sanders pledges not to accept support from any of the political action committees that can raise unlimited sums of money from corporations, unions, associations and individuals. He’s introduced a constitutional amendment to overturn the Supreme Court’s Citizens United decision, which allowed the committees to proliferate, and says one of his criteria for picking Supreme Court justices will be a willingness to overturn the decision.

“That nominee will say that we are going to overturn this disastrous Supreme Court decision on Citizens United. Because that decision is undermining American democracy. I do not believe that billionaires should be able to buy politicians,” Sanders said on “Face the Nation” in May.

Clinton has not ruled out super PAC money and is benefiting from at least two working primarily on her behalf, Priorities USA Action and American Bridge 21st Century.

Clinton has said she would appoint Supreme Court justices “who value the right to vote over the right of billionaires to buy elections” and would push for a constitutional amendment to overturn Citizens United.

Guns

Sanders opposed the 1993 Brady bill, which established federal background checks and a waiting period for potential gun owners.

He’s explained that he represents a largely rural state where guns “mean different things to people” than in urban states. As a result, he’s argued that he could play a role in bringing opposing sides together. He notes that he later voted and supports a ban on semi-automatic weapons, closing the so-called gun show loophole and tightening background checks.

Clinton, in the wake of a community college shooting in Oregon, called for steps on gun control and said she’d act unilaterally if Congress failed to tighten gun show and Internet sales loopholes. She also backs legislation to prevent domestic abusers from buying and possessing firearms and would seek to repeal a 2005 law known as the Protection of Lawful Commerce in Arms Act, which prevents gun manufacturers and dealers in some cases from being sued. Sanders voted for the law in 2005; Clinton voted against it.

Health care

Sanders has championed single-payer, universal health care for all Americans.

Clinton has said she would expand coverage through the existing Affordable Care Act.

Iraq War

Clinton, then a New York senator, voted in October 2002 to authorize military force against Iraq. In her 2014 book, she said she voted “after weighing the evidence and seeking as many opinions as I could inside and outside our government, Democrats and Republicans alike.” She said she got it wrong.

Sanders, then a member of the House of Representatives, voted against the use of force in Iraq, saying in 2002 that he was worried about the “problems of so-called unintended consequences” and that “war must be the last recourse in international relations, not the first.”

Patriot Act

Sanders voted against the surveillance law passed by Congress in 2001 in the wake of the 9/11 terrorist attacks and has voted against its reauthorization since.

He wrote in Time last May that he “believed then and am even more convinced today that the law gave the government far too much power to spy on Americans and that it provided too little oversight or disclosure.”

Clinton voted for the Patriot Act in 2001 as a U.S. senator. She, however, voiced support in May for legislation that President Barack Obama endorsed to end the government’s bulk collection of phone records.

Syria

Clinton called for a no-fly zone in Syria the day after Russia began a bombing campaign in the country to support President Bashar Assad.

“I personally would be advocating now for a no-fly zone and humanitarian corridors to try to stop the carnage on the ground and from the air, to try to provide some way to take stock of what’s happening, to try to stem the flow of refugees,” Clinton told a Boston radio show.

Sanders opposes a “unilateral American no-fly zone in Syria which could get us more deeply involved in that horrible civil war and lead to a never-ending U.S. entanglement in that region.”

Keystone pipeline

Sanders opposes the pipeline, which would carry oil from Canada into the U.S. He helped “lead the effort in the Senate against the Keystone pipeline,” he told “Face the Nation” in June, “because I think, if we’re serious about reversing climate change, you don’t excavate and transport some of the dirtiest fossil fuel in the world.” He said Clinton “has been very quiet on this issue.”

Indeed, Clinton, who as secretary of state oversaw the department’s yet-to-be-completed review, refused for months to say where she stood, saying she was waiting for the White House to make its decision. She announced her opposition on Sept. 22, saying the project is a “distraction from important work we have to do on climate change.”

Minimum wage

Sanders introduced legislation in July to hike the federal minimum wage to $15 an hour.

He called the current federal minimum wage — $7.25 an hour — “a starvation wage,” and said employees who work 40 hours a week “have a right not to be living in poverty.”

Clinton has stopped short of endorsing a federal $15-an-hour measure.

She has supported legislation to raise the federal minimum wage to $12 and backs local efforts in Los Angeles and New York to raise the minimum wage to $15. But she noted in July that “what you can do in L.A. or in New York may not work in other places.”

Trade

Sanders has voted against U.S. trade pacts, saying they’re bad for American workers. He has been a sharp critic of what he calls Obama’s “disastrous” Trans-Pacific Partnership, an ambitious trade pact involving the United States and 11 other nations, and vows to “do all that I can” to thwart the agreement in the Senate.

“This agreement follows failed trade deals with Mexico, China and other low-wage countries that have cost millions of jobs and shuttered tens of thousands of factories across the United States,” he said of the agreement.

Clinton supported Obama’s trade deal as his secretary of state (CNN found she pushed for the pact at least 45 times), but after months of not saying how she stood, Clinton came out in opposition on Oct. 7, saying the pact doesn’t “meet the high bar I have set.”

“The risks are too high that, despite our best efforts, (trade pacts) will end up doing more harm than good for hard-working American families whose paychecks have barely budged in years,” she said.

Sanders declined to criticize Clinton’s hesitance on the issue, saying he was “glad that she reached that conclusion, this is a conclusion that I reached from Day One.”

College

Sanders proposes a “College for All Act” that would make college a right, eliminating tuition at all four-year public colleges and universities.

Sanders says the U.S. should ensure “that every qualified American in this country who has the ability and desire to go to college is able to go to college, regardless of the income of his or her family.”

Clinton’s “New College Compact” promises that students would “never have to borrow to pay for tuition, books and fees to attend a four-year public college in their state,” but it requires that students would have to work 10 hours a week.

(c)2015 McClatchy Washington Bureau. Distributed by Tribune Content Agency, LLC.

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