An expert witness in a federal trial over the constitutionality of Wisconsin's election maps said they were drawn in ways that "significantly diminished" the voting power of Milwaukee's Latino community.

Kenneth Mayer teaches political science at the University of Wisconsin-Madison. He said the 2011 maps shifted the boundaries of two Milwaukee Assembly districts in ways that divided blocs of Latino voters. He said the maps also introduced non-Latino residents into the district, who were more likely than Latinos to vote.

A Latino group said the maps would make it harder for the Latino community to elect candidates sympathetic to their causes.

Rather than develop the maps in an open process, Republican state lawmakers produced them in strict secrecy last year and rushed them through a GOP-led Legislature.

Democrats and an immigrant-rights group have sued, saying the maps were drawn in ways that disenfranchise voters and hurt minorities.

The maps show which voters are located in which voting districts. The district boundaries are adjusted every 10 years to reflect updated U.S. Census numbers.

Assembly Minority Leader Peter Barca acknowledged that Democrats were lining up to oppose new voter maps even before Republicans released them, saying Democrats were hearing rumors and suspecting the worst.

Barca testified Thursday in Milwaukee in the federal trial to determine whether the maps are constitutional.

Barca said Democrats were hearing rumblings that the Republicans would "try to spring something on us," so they began developing a strategy of opposition.

Defense attorney Daniel Kelly countered that Democrats never called an emergency town hall meeting or otherwise sought public input before deciding they wouldn't support maps they hadn't seen.