Jane Addams campaigned vigorously for the new party as a breakthrough in social reform.[273] Gifford Pinchot represented the environmentalists and anti-trust crusaders. Publisher Frank Munsey provided much of the cash.[274] George W. Perkins, a leading Wall Street financier and senior partner of J.P. Morgan bank came from the efficiency movement. He handled the new party's finances efficiently, but was deeply distrusted by many reformers.[275]
The new party was popularly known as the "Bull Moose Party" after Roosevelt told reporters, "I'm as fit as a bull moose".[276] At the 1912 Progressive National Convention, Roosevelt cried out, "We stand at Armageddon and we battle for the Lord."Governor Hiram Johnson controlled the California party, forcing out the Taft supporters. He was nominated as Roosevelt's running mate.[277]
Roosevelt's platform echoed his radical 1907–1908 proposals, calling for vigorous government intervention to protect the people from selfish interests:

To destroy this invisible Government, to dissolve the unholy alliance between corrupt business and corrupt politics is the first task of the statesmanship of the day.[278][279] This country belongs to the people. 