The legacy of the 14th amendment: Not everyone agrees with this expanding interpretation of corporate personhood. In his dissent in Bellotti, Justice William H. Rehnquist wrote that corporations were “artificial” persons rather than “natural” persons, and that granting them the right to political expression could “pose special dangers in the political sphere.” Along similar lines, Justice John Paul Stevens argued in his dissent to Citizens United that “Corporations…are not themselves members of ‘We the People’ by whom and for whom our Constitution was established.” And soon after the ruling, then-President Barack Obama said in his State of the Union address that the decision would “open the floodgates for special interests—including foreign corporations—to spend without limit in our elections.”
Source: https://www.history.com/news/14th-amendment-corporate-personhood-made-corporations-into-people

"One of the points made and discussed at length in the brief of counsel for defendants in error was that "corporations are persons within the meaning of the Fourteenth Amendment to the Constitution of the United States." Before argument, MR. CHIEF JUSTICE WAITE said:

"The Court does not wish to hear argument on the question whether the provision in the Fourteenth Amendment to the Constitution which forbids a state to deny to any person within its jurisdiction the equal protection of the laws applies to these corporations. We are all of opinion that it does. "

Source: https://supreme.justia.com/cases/federal/us/118/394/