MARION — When she was running in the Iowa Democratic caucuses earlier this year, Minnesota U.S. Sen. Amy Klobuchar talked about Democrats building a blue wall.“And Donald Trump will pay for it,” she reminded about 100 people at a get-out-the-vote rally Saturday morning in Marion Square Park.Democrats in Iowa will help seal off the Midwest for former Vice President Joe Biden and other Democrats on the ballot, Klobuchar said three days before voting in the 2020 election ends.“All eyes are on Iowa,” Klobuchar said.The attention Iowa is getting is not just about its six Electoral College votes, but the possibility Iowa voters could cement a Democratic majority in the U.S.