Brooklyn-born Bernie Sanders is a nearly 30-year veteran of Congress who considers himself a democratic socialist. He marched on Washington in 1963, moved to Vermont the next year, and ultimately ran seven statewide races there (losing four, winning three).

In 2016, the Vermont senator became the first Jewish candidate (and first non-Christian) to win a presidential primary. He tells high school students to argue with their parents and teachers, and is an ardent anti-war activist and advocate for military veterans. Sanders has been a popular mayor, a Senate committee chairman, an early social media and filibuster phenomenon, and once recorded a folk album in the style of William Shatner.

Here is where he stands on nine key issues.

Campaign finance: Refuse corporate donations. Limit corporate and interest group spending in campaigns.

Like he did in 2016, Sanders has refused corporate donations and relied on small donors to fund his White House campaign. He has proposed a constitutional amendment that would effectively reverse the Supreme Court’s Citizen United ruling and ban corporations and nonprofits from making unlimited campaign expenditures. He would also require any organization to disclose election-related campaign expenditures of $10,000 or more.

Climate change: Cut carbon emissions by 40 percent by 2030. Tax carbon emissions.

Sanders would institute a carbon tax and aim to slash U.S. emissions by 40 percent by the year 2030, and 80 percent by 2050. He would end all federal subsidies for the gas, oil and coal industries. In addition, he would investigate corporations he sees as “climate deniers” that have spent money raising doubts about climate change. He is a co-sponsor of a resolution calling for a “Green New Deal.”

Education: Free, universal preschool. Free tuition at public colleges and universities.

The Vermont senator would make preschool free for all 4-year-olds, funding the plan by increasing taxes on the wealthy and some Wall Street transactions.

In higher education, Sanders’ “College for All Act” would make tuition at four-year public colleges free for most Americans; two-thirds of the program would be paid for with federal funds, and one-third with state funds. Sanders would pay for the federal portion with what he calls a Wall Street speculation fee of 0.5 percent on stock trades.

Federal Reserve and banks: Break up big banks. Open up the Fed.

Sanders would divide large banks — those with assets worth more than 3 percent of the nation’s GDP — into smaller entities and charge a new fee for high-risk investment practices, including credit default swaps. He would also ban financial industry executives from serving on the central bank’s 12 regional boards of directors.

Guns: Ban assault weapons. Repeal law protecting some gun manufacturers. No federal handgun waiting period.

A gun-control advocate, Sanders would ban assault weapons as well as high-capacity magazines or equipment that allow more than ten rounds to be fired at once. He supports universal background checks and voted for the Manchin-Toomey legislation expanding federal background checks.

In early 2016, Sanders changed his position on a gun law that protects some gun manufacturers and sellers from civil lawsuits. Sanders supported the measure in 2005 while he was serving in the House of Representatives. In 2016, he co-sponsored a bill to repeal that law. In the House, Sanders also voted against the pro-gun-control Brady Bill, writing that he believes states, not the federal government, can handle waiting periods for handguns. He told student reporters from Marjory Stoneman Douglas High School in Parkland, Florida, that he voted no on the Brady Bill because his state preferred “automatic background checks” and not waiting periods.

Health care: Original supporter of “Medicare for All.”

Sanders proposes a government-run health care system for all Americans. He was the lead Senate sponsor of the 2017 “Medicare For All” bill, which would launch universal health care and end employer-provided health insurance.

A report released by the Urban Institute in October found that his single-payer approach would cost $34 trillion dollars over 10 years, more than the total cost of Social Security, Medicare and Medicaid combined.

“Look, I am not denying that we’re going to spend a lot of money,” Sanders told PBS NewsHour in response to criticism about the potential costs of his plans. “But [critics] cannot deny that we’re saving people substantial sums of money by eliminating all premiums.”

Immigration: Path to citizenship for most undocumented immigrants. Restructure, don’t necessarily abolish U.S. Immigration and Customs Enforcement (ICE).

Most undocumented immigrants who are in the country now would receive a path to citizenship under Sanders’ immigration plan. He voted for the 2013 Senate immigration bill that proposed a pathway to citizenship for undocumented immigrants, doubling the number of border patrol officers, and providing an additional 350 miles of border fencing. (That bill did not become law.)

Sanders would like to restructure ICE. But he has not given details and has not gone so far as to say that he thinks the agency should be “abolished,” a position some of his 2020 Democratic rivals have taken.

Social Issues: Abortion should be legal, with few or no government limits. Opposes policies that discriminate based on sexual preference or gender identity.

Sanders is a supporter of abortion rights and voted against a bill to ban abortions after 20 weeks. When asked in 2016 if he would place any limits on abortions, Sanders did not give a specific answer but repeatedly said he was “very strongly pro-choice” and believed the decision was between a woman and her doctor.

On LGBTQ rights, Sanders has touted his early moves in support of the gay rights movement. In 1983, as mayor of Burlington, he approved a resolution declaring “Gay Rights Day;” in 1993, he opposed the military’s “Don’t Ask, Don’t Tell” policy; and in 2000 he supported gay civil unions in Vermont. He opposes President Donald Trump’s push to ban transgender people from the military, and laws that would block transgender people from using the bathrooms of their choice.

Foreign Policy: Use diplomacy to end Syrian conflict. Pull out troops, but in different way from Trump. Cut U.S. support in the conflict in Yemen, hold the Saudi crown prince “accountable” for crimes.

Sanders would pull U.S. troops from Syria, but said he would do it in a different, less “erratic” way than Trump recently announced. He believes diplomacy with Russia and Iran can turn things around in Syria. He also believes the president did not have the right to launch airstrikes against the Assad regime and that war powers must get more rigorous oversight and/or approval from Congress.

A longtime anti-war activist, Sanders voted against the Iraq war resolution in 2002. He regularly called for the U.S. to withdraw troops from Afghanistan and Iraq.

In both Afghanistan and Syria, Sanders has said that he believes the U.S. should remain involved, though with no ground troop presence.

Sanders would end all U.S. support for the Saudi-led war in Yemen, and was a main co-sponsor of the bipartisan bill passed by the Senate to force the Pentagon to end its involvement there. In a tweet, Sanders wrote that Saudi Crown Prince Mohammad bin Salman has murdered activists, heads a despotic regime and should be held accountable.