JEFFERSON CITY, Mo. (AP) -- Missouri House Democrats are expressing concerns about a proposal to increase the state sales tax by a penny to boost funding for transportation projects.

Senators last month approved a proposed a 1-cent sales tax that would generate nearly $8 billion over a decade to fund state and local transportation projects.

The tax would require voter approval and would go back on a statewide ballot after 10 years.

House Democratic leaders critiqued the measure in a letter sent Wednesday to sponsoring Sen. Mike Kehoe.

Democrats say sales taxes have a disproportionate effect on the poor. They also said the measure would not set aside a dedicated portion to projects not involving highways and bridges, and could open the door to legislative involvement in selecting projects.