On the question of equal pay for women, Mitt Romney has planted himself on both sides of the issue, flipping and flopping at the same time.

Mr. Romney says he supports equal pay for women and has “no intention” to repeal the Lilly Ledbetter Fair Pay Act, the 2009 federal law that corrected a notorious 2007 Supreme Court ruling that made it much harder for victims of pay discrimination to challenge their unlawful treatment. Yet he declines to say whether he would have signed that law in the first place, and he calls Gov. Scott Walker of Wisconsin, who this month signed a law repealing a 2009 state wage discrimination law, a “hero.” And when Mr. Romney cites Supreme Court justices he admires, he chooses Justices Antonin Scalia, Clarence Thomas, John Roberts Jr. and Samuel Alito Jr., all of whom voted to deny Ms. Ledbetter justice.

Mr. Romney’s commitment to fair pay will soon be tested. In the coming weeks, Senate Democrats are planning to make another attempt to pass the Paycheck Fairness Act, a much-needed updating and strengthening of the 1963 Equal Pay Act.

The measure was narrowly defeated two years ago by solid Republican opposition, despite strong support from President Obama. The bill would enhance the remedies available for victims of gender-based discrimination and require employers to show that wage differences are job-related, not sex-based, and driven by business necessity. The measure would also protect employees from retaliation for sharing salary information, which is important for deterring and challenging discriminatory compensation.