TOPEKA -- Kansas Rep. Kenny Wilk is adding more armor for his full-scale attack on a controversial new Missouri law on cross-state taxation.

Wilk late last week submitted an unusual opinion request to Kansas Attorney General Paul Morrison. He asked the AG's opinion on whether a recent Missouri law increasing income taxes on out-of-staters who work in Missouri violated their constitutional rights.

Wilk feels their pain. He lives in Lansing, Kan. but works in Kansas City, Mo. and is thus subject to the tax rise. His opinion is noteworthy because AGs are rarely asked about laws in other states.

Republican Wilk, who chairs the Kansas House Taxation Committee, has led the charge against the new law, which should add $11 million to Missouri state revenue. He vowed last month to enact retaliatory taxation on Missourians working in Kansas.

"We will respond to make sure we recoup all - and plus a bit more - of what we're losing," Wilk told the AP several weeks ago. The new law is expected to cost Kansas around $5 million.

Wilk's letter asked Morrison's opinion on whether Missouri's law violated the Privileges and or Immunities clause of the 14th amendment of the U.S. Constitution, the Kansas City Star reported. The clause prevents states from discriminating against other states' citizens.

Missouri Republican House Speaker Rod Jetton supports repealing the law, which he claims was added in carelessly by state senators. He recently asked Kansas lawmakers to delay retaliation until early next year, when the Missouri legislature re-convenes, the Star reported.

Jetton is concerned that Kansas will retaliate with punitive taxes of their own on Show-me Staters before he has time to repeal the law in January.