They include Sen. Bernie Sanders, a self-described Vermont socialist who says corporations, millionaires and billionaires and the big banks are responsible for all of our economic troubles. Bernie is running a distant second to Hillary in the latest polls.
And former Maryland governor Martin O'Malley, a far-left Democrat who slapped dozens of draconian taxes on his beleaguered state (including a levy on rain water), and left it deeply in debt. He says he wants to do to the country what he did to his own state.
Neither of these men have a snow ball's chance in Hell of overtaking Clinton. A recent Quinnipiac University poll shows the former secretary of State drawing 57 percent support from her fellow Democrats.
Sanders, whose socialist rhetoric is popular with much of his party's base, is getting the support of 15 percent of Democrats who want to rebuild Europe's craddle-to-grave welfare state here at home.
O'Malley, little-known outside his state, garners just 1 percent, though he's received gushing press treatment, both for his campaign skills and his far-left liberal record.
Campaign handicapper and ace political analyst Chris Cillizza puts him in third place in the nominating race as a result of his organizational skills to build a better campaign "infrastructure" in the early primary states.
Both Sanders and O'Malley have succeeded politically because they come from heavily liberal Democratic states. Maryland is the second most Democratic state in the U.S., following Massachusetts, and Vermont runs fifth in the top 10 Democratic list.
But even Maryland's liberal voters were fed up with the mess O'Malley had left the state in last year, electing GOP Gov. Larry Hogan, Jr. who pledged to cut taxes, spending and create jobs.
It doesn't appear Clinton has much to fear from either of them -- except their growing appeal to their party's legions of hardcore, far-left voters.
So far, Clinton has been discussing the issues in broad generalities, providing no specifics about her governing agenda -- and getting away with it.
But that could change once Sanders and O'Malley began dishing out the kind of fiery, political red meat they are known for delivering with gusto.
Last Saturday in Iowa City, more than 400 voters turned out to hear Bernie bash Wall Street billionaires. Some said they drove eight hours all the way from Oklahoma City just to hear his ultra-leftist message
That's going to put political pressure on Clinton to beef up her message, perhaps on key issues she had avoided so far on the economy, taxes and spending.
Meantime, the controversy over her secret e-mails is going to resume, now that a judge has ruled that the State Department will have to begin dishing out portions of the 55,000 pages of messages each month that she sent on her privately-run computer system.
This means that the secretive e-mails she wrote outside the government's computer system about official matters will be a running TV news saga well into her presidential campaign.
Throw in nonstop congressional hearings Republicans are planning to hold on the e-mail controversy, at which she will be asked to testify, and she faces a rocky road to the caucuses and primaries to come.
But the biggest issue for Clinton will continue to be the U.S. economy's persistent weakness and decline under the Obama administration.
Last week, the Commerce Department reported that the economy didn't just slow down or stop growing in the first quarter of this year, as first reported. It shrank at a 0.7 percent annual rate.
This is the third time this has happened since the 2008 recession ended.
Here's the way the Wall Street Journal described what had happened:
"Data this week could show the U.S. economy shrank earlier this year, something that usually happens only during recessions. As the advisory firm Capital Economics recently asked, 'Did the U.S. recovery just die without warning?'"
The official definition of a recession is two back-to-back quarters when the economy contracts. Economists and Obama think the economy will resume growing in second quarter, but that assurance is looking a little shaky right now.
The Federal Reserve Bank of Atlanta is now forecasting
that, at best, the economy will grow by just 0.8 percent in April, May and June.
If second quarter GDP comes in at that dismal rate, it means the Obama economy is in a virtual recession, or to be charitable, at best, it's barely growing.
And that's going to result in a lot of damaging political repercussions for the Democrats in the 2015-16 election cycle, and for Clinton's presidential ambitions.
The American people, God bless them, are watching all of this very closely.
So is the Gallup Poll: "U.S. Economic Confidence Index Slides in May," blared the headline over the polling firm's
latest survey Tuesday.
It was the economic confidence index's "third straight month in negative territory," and the "lowest monthly average since November 2014," the polling firm said.
"Americans' confidence in the economy continued to slide," Gallup said. And for good reason: The economy is shrinking. Manufacturing was weak. Gas prices are rising. Consumer spending is flat, as Americans fear the worst.
Obama's been telling us everything's fine. So have the news media and Hillary, too. Now we have fresh evidence that the U.S. economy is in a steep decline and that they haven't been telling us the truth.