It was on that stage last year that the CSC team put in its most potent challenge to Leipheimer.
By midday, it appeared that the most potent challenge Mr. Blaine might face was ennui, as a steady stream of spectators filed past, waving and blowing kisses.
For all the Democrats' threats against Mr. Bush, most agree, at least at this early stage, that the most potent challenge would come from Senator Bob Graham, who has served as governor before.
Many other famous names have already come out strongly against the idea, but the Harry Potter author's vast clout in the children's market makes this the most potent challenge yet to the scheme.
The most potent challenge to America's dominance comes not from the continuing redistribution of global power, but from a subtler change: the new forms of governance and capitalism being forged by China and other rising nations.
A lawyer for the jailed opposition leader, Morgan Tsvangirai, urged a judge in Harare to release his client, arguing that the government of President Robert Mugabe was using Mr. Tsvangirai's imprisonment to silence the most potent challenge to the president's 23-year rule.
A second generation of philosophes, especially the philosopher Jean-Jacques Rousseau, were already testing those limits in the later 18th century; but the most potent challenge to them came from Germany, now finally assuming its full place in the intellectual life of Europe.
The most potent political challenges to the president's conduct of the war on terror have to date come from the Right.Republicans delight in portraying Mr Obama and his government as being soft on Islamic extremists, most recently denouncing his attorney-general, Eric Holder, for allowing the surviving Boston bombing suspect to be read his civilian legal rights.
But the most politically potent challenge is the financial sustainability of Britain's NHS and social care system.
Medrek is seen as the most potent political force challenging the 19-year-old government of Prime Minister Meles Zenawi, whose Ethiopian Peoples Revolutionary Democratic Frontt is expected to win the election comfortably.
