TAMPA, Fla — Republican presidential contender Mitt Romney urged voters here to make President Obama’s State of the Union address Tuesday his last and blamed the Democrat for pushing policies that have raised the nation’s unemployment rate, worsened the housing crises and pushed the nation deeper into a sea of red ink.

Standing under an “Obama Isn’t Working” banner, the former Massachusetts governor said that Mr. Obama, during his first three years in office, has “amassed an actual record of debt, decline and disappointment” and pushed the nation toward a “European-style welfare state.”

Along the way, Mr. Romney said that if elected president, he would approve the Keystone Pipeline project, which he and other conservatives claim will put 20,000 people to work, and pursue tax policies aimed at helping middle-class Americans.

“This president’s agenda made these troubled times last longer,” he said, arguing that it “is critical that we make today Barack Obama’s last State of the Union address.”

Billed as a “prebuttal” to the president’s remarks, Mr. Romney’s remarks came as he works to regroup from Newt Gingrich’s landslide victory in the South Carolina primary, which fed into lingering doubts about Mr. Romney’s ability to rally the party’s conservative base...