By David Nakamura, Updated: Saturday, August 11, 10:55 AM

Republican Mitt Romney made his vice presidential pick official Saturday, but President Obama’s campaign has been running against a shadow Romney-Paul Ryan ticket for months.

In appearances across the country, Obama has gone out of his way to tie Romney to what he described as the “radical” vision of Ryan’s Republican House budget proposal, which the president in April called “social Darwinism” that would pit the poor against the wealthy.

Shortly after Ryan began speaking in Norfolk on Saturday, Obama’s campaign manager Jim Messina issued a statement that again tried to cast the Wisconsin congressman as an ideologue whose extreme views would jeopardize popular middle-class programs.