But the Republicans pressing the Iowa legislation are making a decisive turn away from the smaller, more incremental measures of the past that have, in their view, merely chipped away at abortion rights. They have a new, longer-term goal in their sights: reaching a Supreme Court that could shift in composition with a Republican president in the White House, potentially giving the anti-abortion movement a court more sympathetic to its goal of overturning Roe v. Wade than the current court is.

“We at the state legislatures, especially Republican-controlled legislatures, have a responsibility to kind of reload,” said State Senator Rick Bertrand, a Republican from Sioux City. “We need to create vehicles that will allow the Supreme Court possibly to reach back and take this case, and to take up an anti-abortion case.”

Gov. Kim Reynolds of Iowa, a Republican, has not yet said whether she would sign the bill, though she reiterated through a spokeswoman that she is “100 percent pro-life and will never stop fighting for the unborn.”

A decision from the governor on whether to sign the bill is expected within days.

The legislation does not specify a point in a woman’s pregnancy when abortion is no longer allowed, but would ban abortions if a fetal heartbeat is detected. Experts say such detection is possible at around six weeks of pregnancy.

If the bill becomes law, it could sharply curtail the number of abortions in Iowa, a state of 3.1 million people. According to the Iowa Department of Public Health, of 3,722 abortions performed in the state in 2016, 347 of them occurred before six weeks of pregnancy, the time when many women are newly learning that they are pregnant.