President Obama’s kinder, gentler tone following last week’s mass shooting in Aurora, Colo., disappeared almost entirely during a campaign swing up the west coast this week.

At appearances in Portland Tuesday and in Oakland, Calif., late the night before, Obama issued blistering attacks against Republican Mitt Romney’s plan to cut taxes for the wealthiest Americans. The message has become a cornerstone of the president’s strategy, but it had been absent from the airwaves and speeches in the aftermath of the movie-theater shooting early Friday in suburban Denver that left 12 dead and 58 injured.

Obama also issued a new Web video outlining the choice he believes Americans have between Romney’s vision and his own — and claiming that only his plan to protect federal spending on infrastructure, research and education is good for the middle class.

“That’s not how you grow the economy,” Obama said at a fundraiser in Portland Tuesday afternoon. “That’s part of the debate that we’re going to have over the next three months.”

Obama also took a swipe at the Romney campaign’s effort to make a big deal of the president’s “you didn’t build that” remark in Roanoke this month. Romney is using the remark to portray Obama as a foe of businesses, but the president said the Republican is taking the phrase out of context. He begin airing a new ad Wednesday in which he says the same thing. The campaign also released a longer excerpt of the speech, showing that the controversial quote is part of a longer riff on the ways in which government helps private businesses succeed by providing roads and education and technology investments.

“He’s been twisting my words around to suggest that I don’t value business,” Obama said. But Romney and his advisers “may have tipped a little bit over their skis,” he added.

Obama also slammed Romney for proposing less government regulation of the housing market: “That’s not a plan, that’s a problem.”

The president headed to Seattle after his Portland appearance for another fundraiser. Between the two stops, he was expected to raise about $3 million for the Obama Victory Fund, a joint account for his reelection campaign, the Democratic National Committee and several state committees.