By Mark Willen, Senior Political Editor August 28, 2008 You saw it Tuesday when Hillary Clinton cited a purpose greater than her own ambition -- and again Wednesday when she magnanimously took the floor to personally move that the convention nominate Barack Obama by acclamation. It was there again when Bill Clinton put aside any lingering sore feelings to offer a hard-hitting speech that struck all the right themes, emphaticallly declaring Obama ready to be president. It was also in John Kerry's address, which was tougher and angrier than any speech he delivered on his own behalf four years ago. And it was in Joe Biden's acceptance speech beefing-up Obama's middle class credentials and offering a blistering attack on the foreign policy judgments of John McCain. What you saw was probably the strongest weapon in the Democratic arsenal this year -- an overwhelming will to win. Sponsored Content It's another side of what the pollsters have been calling the "intensity factor." In every poll taken to date, even those showing McCain ahead, the data reveal that Obama's supporters are far more enthusiastic and determined than are McCain's. That's why thousands of young people are volunteering and millions are donating to the Democratic effort. And it's sure to bring a reward in turnout, as Obama supporters show a greater commitment to vote. There's no simple explanation for it, but two factors stand out. One is that Obama has hit a chord, especially with young people and others who still believe there is an important role for government and refuse to accept that partisanship and politics have to be one and the same. For them, it is time for the new generation Obama represents to take over and show there's another way. Advertisement For others, though, it is a feeling that the country really needs to change. Hillary Clinton expressed it when she appealed to her supporters to work just as hard for Obama as they did for her. You didn't do this for me, she reminded them, you did it for the millions of working class people who are struggling. Joe Biden said much the same when he proclaimed, "We don't have to accept a situation we cannot bear." This determination to win -- seemingly based less on beating the other guy and more on the perception that the country is so far off track that anything less than a Democratic win would be a disaster -- is the greatest challenge facing McCain. Republicans have to be braced for a huge turnout -- not just by the Democratic base, but by a wave of new voters and of swing voters tired of the GOP. McCain and the party have to respond next week by wowing the GOP base and persuading the centrists and swing voters that so much is at stake that this is an election they must participate in. That is going to be incredibly difficult because to win over the broad swath of voters tuning in, McCain will have to draw sharp distinctions with President Bush and even with Republican orthodoxy, obviously not something easily swallowed by rank and file party members and conservative regulars. For them, McCain will have to send a message that too much is at stake to allow a demand for the perfect to be the enemy of the good, and that even if he picks someone who is not their ideal, the ticket's vision of where America needs to go is far closer to theirs than that of Obama. McCain can hope that voters will ultimately decide Obama is too risky to be elected president, but that's a dangerous strategy to rely upon -- as Hillary Clinton discovered. His greater chance lies in making the case that he, too, can offer change and that it will be a better, safer, wiser change. No easy task, given the widespread distrust of Republicans at the moment.