DENVER—A Colorado lawmaker wants to make it more difficult for defense attorneys to prove their clients are not guilty by reason of insanity.

Republican Rep. Frank McNulty is sponsoring legislation that would put a greater burden on defense teams to prove insanity by clear and convincing evidence, instead of the current standard where prosecutors have to prove defendants are sane.

The bill is up for its first vote in a House committee on Wednesday.

The proposal seeks to address high-profile cases where the insanity defense is expected. One of those cases involves Aurora theater shooting suspect James Holmes. His attorneys have said he's mentally ill.

Holmes has not entered a plea yet.