Why did mayoral prospect Monica Vernon change from Republican Party to Democratic Party?

First it was U.S. Sen. Arlen Specter. Now it's Cedar Rapids council member Monica Vernon.

In recent days, Specter changed his political party affiliation from Republican to Democrat as he readies to try to keep his seat in the U.S. Senate from the state of Pennsylvania. He said he couldn't win the Republican primary there in a Republican Party that he said had moved to far to the right.

But why is Vernon -- a long-time Republican with a husband, Bill, who as recently as 2008 was a member of the party's state central committee -- moving to the Democratic Party?

Vernon, who is the second year of a four-year term as District 2 council member, has been among a group of people considering a run this year for Cedar Rapids mayor, which, like other City Council seats in Iowa, is a non-partisan post.

This year's mayoral race, though, surely will come with a partisan flavor.

To date, only Ron Corbett, a former Republican speaker of the Iowa House of Representatives, has announced that he is running for mayor.

On Monday, Linn County Supervisor Linda Langston, a prominent Democrat, said Democrats were urging her to take on Corbett. She said she was considering a mayoral race, but was not yet convinced she would run.

Council member Brian Fagan is another person mentioned as a possible mayoral candidate, and Fagan is registered to vote without political party. He changed his registration to Republican so he could compete in the January 2008 presidential caucuses, and he changed it to Democratic so he could vote in the June 2008 primary, the Linn County Auditor's Office reports.

The county office said it processed Vernon's change of party from Republican to Democratic just today, Tuesday.