Barack Obama, vowing to choose a vice presidential candidate who would be qualified for the presidency and who would not fear to express his own views even if they differ from those of the Oval Office occupant, feels he's found the right combination in veteran Delaware Sen. Joseph Biden. This week the two will attempt to rally their troops at the Democratic National Convention in Denver.

Biden, a formidable foreign policy expert and an eloquent voice of and for working families, seems to meet the criteria. Chairman of the Senate Foreign Relations Committee, and a former chairman of the Judiciary Committee, he went to the Senate over 30 years ago and has earned bipartisan respect.

His opening salvo at a Saturday rally in Springfield, Illinois -- where Obama began his campaign 19 months ago -- included a recognition of his roots, a pledge of unity with Obama and a glimmer of what is to come, namely some criticism of his long-time friend and Senate colleague, Arizona Republican John McCain, who'll get his party's nomination next week.

In a way, McCain faces the same challenge Obama does. With over 20 years in the Senate and considerable bona fides in foreign policy, the Republican also will be looking for balance. He surely has in mind a running mate with strengths in domestic policy and economics -- not McCain's best points thus far.

The choice of Biden has been met with enthusiasm and marks the beginning in earnest of the general election campaign. Vice presidential nominations typically don't make much of a difference in presidential races. But Biden's presence on the Democratic ticket may temper criticisms of Obama's lack of Washington experience. More difficult for Democrats will be bringing supporters of Hillary Clinton, who narrowly lost the nomination to Obama, into the tent.

As the convention proceeds, voters and delegates will monitor how that process is going. The party will pay tribute to its idols -- particularly the Kennedys. Speakers will denounce President Bush and attempt to tie McCain to his failures. Special-interest groups traditionally allied with Democrats (both parties have plenty of them, of course) will have time to speak.

But what should take place this week, and next, is a constructive attempt by each major party to detail and share a vision of how to cope with the considerable challenges left to the next president in the stormy wake of the current one -- two wars, a mortgage crisis, gas prices and the dependence on foreign oil, health care, the general economic downturn. And, perhaps most disturbingly, a feeling on the part of this generation of working Americans that their children and grandchildren might face harder times than they have.

Obama and Biden will try this week to make clear their vision. They owe the people, Republicans and Democrats alike, no less.

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