A new lawsuit in federal court seeks to overturn Alaska's strict limits on donations to political candidates and groups using a pair of recent U.S. Supreme Court decisions as precedents.

The suit, filed by an Anchorage Republican district and three supporters of Republican candidates, challenges the state's $500 annual cap on individuals' donations to candidates, as well as three other contribution limits.

If the lawsuit prevails, it could reshape the political landscape for next year's state legislative elections by allowing donors to spend more money on their favored candidates. A trial is tentatively scheduled for late April before U.S. District Judge Timothy Burgess.

The suit, which was first reported by television station KTUU, was filed last week.

According to lead attorney Kevin Clarkson, the case started when David Thompson, a Wisconsin resident, "ran into a brick wall" when he tried to contribute to the campaign of his brother-in-law, Rep. Wes Keller, R-Wasilla.

Thompson said he couldn't donate to Keller because of a law that bars candidates from collecting more than $3,000 annually from Outsiders.

The three other plaintiffs complained of similar confrontations with the maximum contribution limits in Alaska law:

• Aaron Downing, a Mat-Su resident and retired electrical contractor, said he wanted to give more than the legally allowed $500 to a Republican House candidate and a Mat-Su Borough mayoral candidate in recent elections.

• Jim Crawford, an Anchorage resident, wanted to give more than $500 this year to the Alaska Miners Association's political action committee, but couldn't under state law.

• The Republican group in House District 18 in Anchorage says it couldn't donate to city mayoral candidate Amy Demboski's campaign this year because she had already raised the maximum of $5,000 from other GOP groups.

Clarkson, their attorney, has often represented conservative causes and is seeking to fill an expected vacancy on the Alaska Supreme Court.

"We took a look at the provisions we thought were most challengeable," Clarkson said. "The landscape of this law has changed substantially in the last 9 to 10 years."

The $500 annual cap on donations by individuals to candidates dates back to 1997, when it was set by the Legislature. Lawmakers raised the cap to $1,000 in 2003, but a 2006 citizens initiative reduced it back to $500, where it's remained ever since.

Only Montana and Colorado have lower limits for state legislative candidates, while no state has a lower limit for gubernatorial candidates — though Alaska candidates can raise $1,000 from individuals if they start fundraising the year before the election, using the full two-year election cycle.

Alaska's limits are so strict they unconstitutionally limit free speech, the lawsuit argues.

In making that argument, Clarkson's initial briefs are peppered with references to the two recent Supreme Court rulings, which equated free speech with contributing money to campaigns.

One, the 2010 Citizens United decision, invalidated a ban on corporate and union spending as long as it's not directly coordinated with a candidate — a ruling that is reshaping federal campaigns, including next year's presidential election.

The second ruling, in the 2014 McCutcheon case, struck down a $120,000 limit on individuals' total contributions to candidates and political parties during a two-year election cycle.

In McCutcheon, Chief Justice John Roberts wrote in a 5-4 opinion that there's only one legitimate reason for the government to restrict campaign contributions, which is to stop corruption.

Spending large amounts of money on elections doesn't give rise to "quid pro quo" corruption — bribery, essentially, or the exchange of cash for specific political favors — Roberts added.

That majority view, however, has been rejected by other justices like John Paul Stevens, who wrote a dissenting opinion in the Citizens United case. The idea that bribery could be treated separately from other "improper influences," Stevens said, didn't match "the theory or reality of politics."

Clarkson repeats Roberts' argument in his own filings, which also cite a 2006 U.S. Supreme Court ruling that struck down Vermont's low campaign contribution limits. The lawsuit doesn't specify what would be more appropriate limits for Alaska; Clarkson says that decision would be up to the Legislature, though he thinks there's no reason to keep them below the federal $2,700 per-election cap.

The state has not yet filed a point-by-point response to the plaintiffs' arguments. But Assistant Attorney General Margaret Paton-Walsh said the state believes it can show the contribution limits are narrowly crafted to prevent corruption.

"We do plan to defend the constitutionality of the statutes," she said in a phone interview Thursday.

State Democrats panned the lawsuit. In a prepared statement, state party Chairman Mike Wenstrup said the effort "seeks to diminish the voice of average people."

Sen. Bill Wielechowski, an Anchorage Democrat and an attorney, said the Supreme Court's view of election spending and corruption, as articulated by Roberts and repeated in the new lawsuit, applies only "in fantasyland."

"It's not realistic," he said in a phone interview.

Raising Alaska's contribution limits, Wielechowski added, would be "terrible policy." But legally, he said, the challenge presents a question and could be a close decision if it goes to the U.S. Supreme Court.

There have been relatively few federal challenges to contribution limits in other states, said Stephen Spaulding, an attorney at the Washington, D.C.-based advocacy group Common Cause, which seeks stricter campaign finance laws and aims to reverse decisions like the one in the McCutcheon case.

So far, Spaulding said, the Supreme Court has largely left state campaign finance regulations alone, with the exception of the 2006 Vermont ruling. But he called the Alaska lawsuit a "dangerous case" because of the court's recent posture toward contribution limits.

"I'm not going to sleep well at night until this case is dismissed," Spaulding said.

Clarkson, the attorney representing the plaintiffs, said his side plans to call experts including Clark Bensen, an attorney who was involved in the Vermont case.

Bensen is a member of the Republican National Lawyers Association and is a former operative with the Republican National Committee.

Keller, the brother-in-law of one of the plaintiffs, is himself connected to a national conservative organization — he's the state chairman for the American Legislative Exchange Council, an organization with legislator members and corporate sponsors that drafts model laws with a strong conservative and pro-business bent.

But Clarkson maintained the lawsuit was not explicitly partisan.