(CNN) Joe Biden is (finally) running for president. And while he is a clear top-tier candidate, he's got issues to deal with from his age (he's 76) to his centrist approach to policy. But it's possible that none of those things are the biggest immediate problem facing the early days of his campaign.

What might that problem be? Money.

Yes, on its face, it seems ridiculous. After all, Biden spent eight years as Barack Obama's vice president. And more than four decades in the Senate before that. If anyone should be able to raise money, you would think it would be someone with a resume like Biden's. But that assumption overlooks two very important problems built into Biden and his fundraising operation: 1) He's never been a prolific fundraiser in past campaigns, largely because he makes no secret that he loathes asking for money and 2) The model of fundraising for presidential campaigns has radically changed in the last 10 years.

On the first issue: Biden was first elected in 1972 with 51%. But in all of his reelection races he never won with less than 58% of the vote -- and wasn't seriously challenged. In his last Senate race in 2008 , Biden raised just north of $7 million -- not an insignificant sum but not the tens of millions that other Senate candidates -- Elizabeth Warren and Beto O'Rourke, to name two -- have collected in previous runs.

When Biden ran for president in 2008, he collected $14 million total -- well off the frontrunners. He was never seen as a serious candidate in that contest. Twenty years before, in the 1988 presidential race, Biden collected $4 million. He was considered one of the race's frontrunners before being run out of the contest due to allegations of plagiarism.

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