Election rules in Kansas and Arizona that require proof of U.S. citizenship are set to take effect in coming weeks in state primaries. Some people will be barred from voting in state races, even as the federal government allows some of them to vote in congressional races.

The split system is the result of a growing battle between federal officials and a handful of states over the necessity of verifying that a newly registered voter is a U.S. citizen.

Kansas and Arizona say the federal registration process doesn’t rigorously check citizenship. They have established their own verification systems and are barring people who register using the federal system from voting this month for such offices as governor and local posts.

In recent years, mostly Republican-controlled states have tightened voting rules, including requiring voters to produce picture identification at the polls, arguing it prevents fraud.

“There is a very real problem with aliens being registered to vote,” said Kansas Secretary of State Kris Kobach, who said about a dozen states are likely to pass such measures in coming years.

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