The Supreme Court on Monday upheld regulations barring foreign nationals from contributing to U.S. campaigns. The ruling in Bluman v. FEC applies to foreign citizens who live and work in the U.S. temporarily, not to naturalized citizens or permanent residents (green card holders).

But court rulings on at least three other lawsuits challenging campaign finance laws could still be on the horizon, potentially altering the playing field for the November election, according to BNA's Money & Politics Report. The new cases challenge bans on campaign contributions from government contractors and corporations, as well as rules governing political committees and express advocacy.

According to BNA, the U.S. Court of Appeals for the Fourth Circuit has scheduled oral arguments for the March 20-23 session on both U.S. v. Danielczyk, a case challenging the constitutionality of a ban on corporate campaign contributions, and Real Truth About Obama (RTAO) v. FEC, a challenge to FEC rules dictating which organizations and activities can be regulated under campaign finance law.

Danielczyk involves a criminal case brought by federal prosecutors against William Danielczyk, a supporter of Hillary Clinton's 2008 presidential campaign, over contributions from Galen Capital Group, which he controlled at the time. In RTAO v. FEC, the appellate court will review an earlier decision upholding the FEC's definition of "express advocacy" and its determination of who has political committee status. Both rules are integral in determining which groups are subject to campaign finance regulation and FEC or Justice Department enforcement, according to BNA.

According to the FEC, express advocacy arises when communications "include a message that unmistakably urges the election or defeat of a clearly identified candidate."

In the third case, Wagner v. FEC, lawyers representing government contractors intend to ask a federal court by the end of January to block the ban on campaign contributions from individuals with government contracts, BNA reported.

Meanwhile, some lower courts have taken steps to roll back deregulation in the wake of Citizens United and subsequent cases advocating to ease campaign finance restrictions.

The Montana Supreme Court ruled in late December that the state's ban on corporate campaign contributions is constitutional, despite the precedent set by Citizens United, BNA noted. And in Van Hollen v. FEC, Maryland Democratic Rep. Chris Van Hollen, backed by campaign reform groups, is pushing for tougher FEC rules for disclosing who paid for electioneering messages, BNA said. A hearing is scheduled for Wednesday.