Following last week's Republican calamity in Cleveland, the Democratic National Convention rolls into Philadelphia this week with big opportunities and big challenges. Many Democrats will come with enthusiasm, but also with reservations.

Unlike the Republican Convention's speaker line-up, which was backfilled with Mr Donald Trump's children because there were so few party heavyweights to anchor it, the Democratic Convention will have a litany of A-listers: The President, the First Lady, Mr Bernie Sanders and former President Bill Clinton among them.

These speakers will paint a vastly different picture of the United States and its future than the unremittingly dark and dangerous one portrayed by the Republicans.

There will also likely be less acrimony in Philadelphia as the Democrats review the failed stagecraft of Cleveland and work hard not to replicate it. But, all is not roses for the Democrats.

The presumptive presidential nominee, Mrs Hillary Clinton, has a battered image - partly due to a concerted effort by Republicans to batter it, and partly the result of her own poor choices. Two-thirds of registered voters don't believe that she's honest and trustworthy, and trustworthiness is one of those attributes that tends to be difficult to quickly and easily alter.

Mrs Clinton's honesty numbers are even worse than Mr Trump's, but not by much. They both have some unbelievable negatives. As The New York Times reported earlier this month: "In a development not seen in any modern presidential contest, more than half of all voters hold unfavourable views of the two major party candidates and large majorities say neither is honest and trustworthy. Only half of voters say Mrs Clinton is prepared to be President, while an astonishing two-thirds say that Mr Trump is not ready for the job - including four in 10 Republicans."

But, being about as bad as Mr Trump is hardly a good thing. Mr Trump is a horrible candidate who shouldn't have a shot, but in this race he does. Although Mrs Clinton remains the favourite to win in November, the race is too close for comfort. There are paths to victory - uphill though they may be - for Mr Trump to win.

(Just typing that sent shivers down my spine. The idea that a man who used a racist attack on a judge in one of his own cases might get to pick the next one - or even two or three - Supreme Court justice is in itself unfathomable. The fact that he's even competitive makes me question the electoral competency of America.) Too many voters find themselves in the worst possible position: They have a choice between a Republican of whom they are frightened and disgusted and a Democrat of whom they are leery and not enthusiastic about.

Last week, Mrs Clinton had a chance to shake up the race with her vice-presidential pick, but instead she chose the safer route, choosing the Democratic centrist Mr Tim Kaine.

Mr Kaine has his virtues - he is solid and affable, a solid liberal from the crucial state of Virginia - but this is not the sort of pick that taps into the progressive populism sweeping the party or the expansive diversity that constitutes the party.

Mr Kaine reinforces Mrs Clinton's "steady hand" message, but that is a message, however valid and necessary, that's completely devoid of sizzle.

Mr Trump is campaigning on fear, change and winning, all intense and even seductive ideas, even though his proposals are insular, unrealistic or hollow. "Steady" just doesn't have the same emotional appeal. And although I hate to boil a historic election, and monumental policy challenges, down to emotions, I've been around long enough to know that this sort of visceral sensibility can swing elections.

The Democrats also have to deal with the resurgent idea of a primary process and party apparatus that favoured Mrs Clinton and wasn't completely fair to Mr Sanders.

This was reignited in the conversation last week when WikiLeaks released nearly 20,000 internal e-mails from the Democratic National Committee in which some officers expressed antipathy and outright hostility to Mr Sanders and his candidacy.

No matter who one supported during the primaries, or even what party one aligns with, this should turn the stomach. This kind of collusion is precisely what is poisoning our faith in politics.

This reinforced the feeling of many that the system was rigged from the beginning.

CNN reported on Sunday that in the wake of the scandal, the tainted party chairman, Ms Debbie Wasserman Schultz, agreed to step down from her role at the conclusion of the convention.

But the injury is already inflicted.

These leaks further damage an already-damaged faith in the Democratic nominating process. In March, the Pew Research Centre found that 42 per cent of Republican voters had a positive view of the primary process, compared with 30 per cent of Democrats. The share of Democrats expressing a positive view of the primary process declined 22 percentage points (from 52 per cent) in February 2008. Republicans' views are little different than in 2000 or 2008. What are those Democratic voters supposed to do if they don't trust the candidate, the party or the process, even if they view The Donald as the Devil? This is one of the convention's conundrums.

NEW YORK TIMES