The Privileges and Immunities Clause of the 14th Amendment (ratified in 1867) states:

The Privileges and Immunities Clause gives each citizen the same protection against abridgments by state governments as each citizen already possessed relative to abridgments by the federal government.

The National Popular Vote bill does not abridge any existing constitutional privilege or immunity. In particular, the people have no federal right to vote for President.⁹⁷ The people acquired the vote for President as a result of the enactment by state legislatures of state laws, on a state-by-state basis. In the nation's first presidential election in 1789, only five states permitted the people a vote for presidential electors. Indeed, at the time when the 14th Amendment was ratified (1867), state legislatures still occasionally appointed presidential electors themselves, without a vote by the people (e.g., in 1860, 1868, and then for the last time in 1876). As the U.S. Supreme Court stated in the 1893 case of McPherson v. Blacker:

Section 2 of the 14th Amendment says:

Section 2 of the 14th Amendment provides a remedy in the form of reduced congressional representation if any person's right to vote is denied or abridged by any state.

The National Popular Vote bill does not deny or abridge any person's right to vote for any other office. Section 2 manifestly does not preclude a national popular vote for President.

Note also that section 2 does not give the voters the right to vote for President. At the time when the 14th Amendment was ratified (1867), state legislatures were still appointing presidential electors themselves, without a vote by the people (e.g., in 1860 in South Carolina, 1868 in Florida, and 1876 in Colorado). The congressional act providing for Colorado's statehood in 1876 specifically mentioned that the Colorado legislature could appoint the state's presidential electors for the 1876 election. Thus, there were examples of state legislatures appointing presidential electors before, during, and after the time when the 14th Amendment was debated and ratified. As the U.S. Supreme Court stated in the 1893 case of McPherson v. Blacker:

The Due Process Clause of the 14th Amendment says:

The National Popular Vote bill does not deny any person of life, liberty, or property. Voting for President is not a "liberty" granted by the U.S. Constitution, and it certainly is not "life" or "property."

The Equal Protection Clause of the 14th Amendment says:

Some have argued that it is not permissible, under the Equal Protection Clause, for some states to close their polls at 6:00 p.m. while others close at 9:00 p.m; for some states to conduct their election entirely by mail while other states conduct their (non-absentee) voting at the polls; and for some states to permit violent felons to vote while others prohibit it (absent a pardon). However, the U.S. Constitution does not require that the election laws of all 50 states be identical in virtually every respect. In particular, the Equal Protection Clause of the 14th Amendment only restricts a given state in the manner in which it treats persons "within its jurisdiction." The Equal Protection Clause imposes no obligation on a given state concerning a "person" in another state who is not "within its [the first state's] jurisdiction." State election laws are not identical now, nor is there anything in the National Popular Vote compact that would force them to become identical. Indeed, the U.S. Constitution permits diversity of election laws among the states because it explicitly gives the states control over the conduct of presidential elections (article II) as well as congressional elections (article I). The fact is that the Founding Fathers intended, and the U.S. Constitution permits, states to conduct elections in diverse ways.

The National Popular Vote bill does not violate the Equal Protection Clause of the 14th Amendment.