The Supreme Court on Monday turned down a request that it consider lifting a long-standing ban on corporations making direct contributions to political candidates.

Less than a week after finding unconstitutional a total limit on how much individuals can contribute to political candidates and parties, the justices without comment declined to review an Iowa law that bans contributions from corporations.

The challenge by the Iowa Right to Life Committee said the ban could not be reconciled with the court’s decision in Citizens United v. Federal Election Commission. That 2010 ruling said corporations and unions had a free-speech right to unlimited spending on elections.

But that decision did not touch on direct contributions to candidates, and an appeals court considering the case said it is up to the Supreme Court to make such major changes to campaign finance laws.

The organization had a second issue it wanted the court to consider: Whether the law unfairly discriminated against corporations because the state’s ban on contributions does not apply to labor unions.

The case was brought by James Bopp, an Indiana-based lawyer who has been responsible for bringing many of the challenges to Watergate-era campaign finance laws that have resonated with the Supreme Court’s conservative majority.

Since Chief Justice John G. Roberts Jr. and Justice Samuel A. Alito Jr. have joined the court, the justices have struck down a series of restrictions on campaign contributions that they say impinge on free-speech rights.

The most recent was last week’s decision in McCutcheon v. Federal Election Commission . The 5-to-4 decision struck down limitations on the two-year total an individual may give to federal candidates, political parties and committees, which had been capped at $123,200.

It did not change the amount an individual can give a specific candidate, which remains $5,200 for the election cycle.

The case the court declined to accept is Iowa Right to Life Committee v. Tooker .