Amending the Constitution is no easy feat. But long odds haven't stopped Democrats and Republicans alike from calling for change on the campaign trail.
There have only been 27 amendments to the legendary legal document since the Founding Fathers—quite literally—put pen to paper. And that's with good reason: Even the most routine way of amending the Constitution is very nearly impossible. An amendment must win consent from two-thirds of the Senate and House before being sent to the states for final approval.
Still, the mere suggestion of altering America's bedrock law can make a splash in a crowded 2016 field. And as long as presidential candidates vie for attention, suggestions for changing the Constitution may continue to materialize even if actual amendments do not.
Here are the ways that 2016 presidential candidates have voiced support for amendments to the Constitution or pushed an agenda that could ultimately upend it:
Ending birthright citizenship
Donald Trump set off a firestorm of debate over the weekend by calling for an end to birthright citizenship, a right granted to children of illegal immigrants born in the United States by the 14th Amendment to the Constitution.
For now, Trump is not explicitly advocating a constitutional revision, but that hasn't stopped other 2016 Republicans from doing just that.
Ted Cruz set himself apart from much of the GOP field on Wednesday by voicing support for altering the 14th Amendment to end the policy. "Absolutely," Cruz said when asked during an interview if he would be in favor of a constitutional change to achieve that aim.
So far Cruz appears to be alone in backing a constitutional amendment to end birthright citizenship on the campaign trail. But he's not the only Republican eyeing the White House to have called for a constitutional change to overturn the policy.
In 2011, Rand Paul sponsored a congressional resolution to amend the Constitution and end automatic birthright citizenship for children if both parents were illegal immigrants. A year earlier, Lindsey Graham called birthright citizenship "a mistake," saying, "We should change our Constitution and say that if you come here illegally and you have a child, that child's automatically not a citizen."
Scott Walker, Bobby Jindal, Ben Carson, and Rick Santorum have either criticized birthright citizenship or called for an end to the policy, but they have not explicitly called for changing the Constitution in the aftermath of Trump's vehement opposition.
Letting states define marriage
Striking directly at the Supreme Court's verdict that same-sex marriage is legal, Scott Walker and Ted Cruz have both voiced support for a constitutional amendment that would let states decide the definition of marriage.
"As a result of this decision, the only alternative left for the American people is to support an amendment to the U.S. Constitution to reaffirm the ability of the states to continue to define marriage," Walker said after the court verdict.
Cruz, meanwhile, has introduced the "Restoration of Marriage Amendment" in April. The measure, per the Texas senator's website would amend "the Constitution to guarantee the right of the people to define marriage in their laws as the union of one man and one woman."
While Cruz and Walker would let states define marriage, Rick Santorum has staked out a position to the right of both 2016 contenders by calling for a constitutional amendment that would create "a national standard for marriage" by defining marriage as strictly a union between a man and a woman.
Overturning Citizens United
Democrats looking toward 2016 rarely miss an opportunity to attack the flood of money in politics—and the leading presidential contenders on the Left think that a constitutional amendment may be the thing to fix what they say is a serious problem.
Hillary Clinton and Bernie Sanders both support a constitutional amendment to overturn the Citizens United Supreme Court verdict that paved the way for corporations to spend unlimited amounts of money in an attempt to influence the outcome of elections.
Earlier this year, Sanders introduced a constitutional amendment to roll back the high Court ruling, calling Citizens United "one of the most disastrous decisions" in the history of the Supreme Court.
Clinton has also made campaign-finance reform a key element of her 2016 platform. "We need to fix our dysfunctional political system and get unaccountable money out of it once and for all—even if it takes a constitutional amendment," the Democratic candidate said at a campaign stop in April.
But it's not just Democrats eyeing the White House who want to reverse the court decision by changing the constitution. Lindsey Graham has similarly called for a constitutional amendment to overturn Citizens United on the 2016 trail.
Balancing America's budget
Nearly every leading 2016 Republican contender has at one time or another backed a constitutional amendment that would compel Congress to balance the budget.
Jeb Bush, John Kasich, Marco Rubio, Ted Cruz, Rand Paul, and Rick Santorum have all called for a balanced-budget constitutional amendment, a measure that would require Congress to make sure that it does not spend more money than it pulls in from taxes each year.
Republicans have long called for Congress to rein in spending. But pushing a constitutional change as a way to get the nation's finances in order is a way for 2016 contenders to burnish their conservative credentials while showing how dire they believe the situation is even if such an amendment would be unlikely to ever become enshrined in the Constitution.
Taking aim at the Affordable Care Act
Expressing opposition to President Obama's signature health care law, Marco Rubio introduced a constitutional amendment in 2013 that would invalidate the law's controversial "individual mandate," a provision that requires most Americans to purchase health insurance or pay a penalty.
Rubio's amendment would amend the Constitution to say that "Congress shall make no law that imposes a tax on a failure to purchase goods or services."
Changing the way Congress works
Rand Paul has signaled support for constitutional amendments that would set term limits for members of Congress and ensure that Capitol Hill abides by the laws that it passes.
"To fix Washington, we must end business as usual," Paul proclaims in a video on his 2016 campaign website. "I have a constitutional amendment that says that Congress shall pass no law that exempts themselves, and to change the culture of Washington, we should pass term limits and send career politicians packing."
None of that is likely to pass. But campaigning on the constitutional amendments gives Paul an opportunity to rail against Washington and cast himself as a political outsider intent on reform.