At this time four years ago, Barack Obama’s campaign had about 30 field offices up and running in Iowa, compared to six offices for Republican presidential candidate John McCain.

Obama’s campaign has had eight Iowa field offices open this summer and is rolling out another 26 offices around Iowa this weekend. So far, Mitt Romney’s campaign has ten Iowa field offices, in addition to the unified Republican headquarters in Urbandale.

After the jump, I compare the field office locations for each presidential campaign, grouped by Iowa Congressional district. Where relevant, I’ve also noted competitive Iowa House and Senate districts near the Obama and Romney field offices, although I doubt either presidential campaign will do much for down-ticket Democratic or Republican candidates.

The redistricting process and several Republican retirements have created many pickup opportunities for Iowa House Democrats. The devastating 2010 election left them nowhere to go but up in the lower chamber, where Republicans currently enjoy a 60 to 40 majority. Relatively few sitting House Democrats represent vulnerable districts.

Speaking to activists at the Polk County Democratic convention on March 10, I heard lots of optimism about the House races. After the jump I’ve posted some early thoughts on the seats up for grabs.

Republicans have recruited a strong candidate for the open Iowa House district 14, which covers most of Sioux City’s west side, part of the north side and some of the downtown neighborhood.