LANSING, Mich. -

Democrats are getting ready to gather at more than 200 caucus sites around the state to formally choose Barack Obama as their presidential favorite.

Registration will be from 9 a.m. to 11 a.m. EDT Saturday, with voting beginning immediately afterward.

Voters must indicate at registration that they're participating as Democrats, but there's no requirement to join the party or even be a registered voter. Participants have to be eligible to vote in November, a requirement that will allow those not quite 18 to vote in the caucuses.

Participants must go to their assigned caucus site, which can be found at .

Democrats who voted in the Feb. 28 presidential primary can still attend the caucuses and vote.

Michigan native Mitt Romney narrowly won the state's Republican presidential primary.