HOW TO FIX THE PROBLEM
State laws that award all of a state's electoral votes to the presidential candidate getting the most votes inside each state are the reason it is possible to win the Presidency without getting the most votes nationwide.
The state-by-state winner-take-all method of awarding electoral votes is not in the U.S. Constitution.
Winner-take-all was enacted by the states under their authority under Article II of the U.S. Constitution, which says, "Each State shall appoint, in such Manner as the Legislature thereof may direct, a Number of Electors...."
The winner-take-all method of awarding electoral votes was not the Founding Fathers' choice. Winner-take-all was never debated at the Constitutional Convention or mentioned in the Federalist Papers. It was used by only three states in the nation's first presidential election in 1789 (and repealed by all three by 1800).
State winner-take-all laws may be changed in the same way as they were originally enacted -- namely by action of the state legislature. It does not take an amendment to the U.S. Constitution to change a state law. Indeed, the winner-take-all method was not enacted by means of a federal constitutional amendment.
The National Popular Vote interstate compact will go into effect when enacted by states with a majority of the presidential electors—that is, 270 of 538. After the compact comes into effect, each individual voter in all 50 states and DC will acquire a direct vote in the choice of all of the presidential electors from all of the states that enacted the compact. The presidential candidate supported by the most voters in all 50 states and DC will therefore win a majority of the presidential electors in the Electoral College (at least 270), and therefore become President.
The National Popular Vote bill is an achievable political goal. Fifteen states and the District of Columbia have already used their constitutional powers to replace current winner-take-all laws with the National Popular Vote interstate compact. These 16 jurisdictions have 196 electoral votes. This is only 74 short of the 270 needed to activate the bill.
The bill has been enacted into law by 5 small jurisdictions (Delaware, Hawaii, Rhode Island, Vermont, and the District of Columbia), 8 medium-sized states (Colorado, Connecticut, Maryland, Massachusetts, New Jersey, New Mexico, Oregon, Washington state), and 3 big states (California, Illinois, and New York). It has also passed one house in 8 additional states with 75 electoral votes (AR, AZ, ME, MI, MN, NC, NV, OK). A total of 3,408 state legislators among all 50 states have endorsed it.