Barack Obama leads John McCain 52 percent to 40 percent in Iowa, according to a Des Moines Register Iowa Poll released Sunday.

The poll, conducted Sept. 8 through 10 after both parties’ conventions, also included Libertarian Bob Barr, at 2 percent, and Ralph Nader at 1 percent, and has a 4 percent margin of error.

In the U.S. Senate race, incumbent Tom Harkin leads Republican challenger Christopher Reed, 53 percent to 34 percent.

Other key findings in the Register article:

  • Independents prefer Obama to McCain, 49 percent to 36 percent.
  • Voters under 35 prefer Obama by two to one.
  • Obama leads among women, 53 percent to 39 percent for McCain.
  • Republicans are more satisfied with McCain’s running mate, Sarah Palin, than Democrats are with Joe Biden, Obama’s vice presidential pick.
  • President Bush’s approval rating with Iowans is at an abysmal 25 percent, with 71 percent disapproving.
  • Senator Chuck Grassley remains popular with Iowans, at 69 percent approval.

The rollout of Iowa Poll presidential results usually signals a weeklong series of Register stories featuring polls on other races and issues.