There's a reason President Obama has spent part of his time during "fiscal cliff" negotiations appealing to voters: They are Democrats' ace on the hole.

In fact, poll after poll shows Democrats have the American public on their side when it comes to the major issues at hand in the fiscal cliff talks.

And more and more, it's looking like Republicans have very little leverage -- at least, when it comes to public sentiment.

Here are three reasons why:

1. The central issue of the fiscal cliff talks favors Democrats overwhelmingly

So far, the dominant issue has been whether Republicans will vote to raise tax rates on the wealthiest Americans. And depending upon which poll you look at, as much as two-thirds of the American public supports this as a way to deal with the country's budget issues.

Democrats have had better messaging on this than in previous clashes. In the past, they might have just come away looking like tax-raisers. Today, they emphasize that both they and Republicans agree on renewing the tax cuts for the 98 percent, and Republicans are preventing a deal because they want to renew the cuts for the top 2 percent. That's a winning argument, according to the polls.

It's also why a few Republicans, including Rep. Tom Cole (R-Okla.), have edged away from the party's firm anti-tax hike position. "Some people think that’s our leverage in the debate; it’s the Democrats’ leverage in the debate," Cole said. More and more, Cole is looking like he's got his finger on the pulse.

2. Even the secondary issues don't favor the GOP

Aside from balking at raising taxes on the wealthy, Republicans want entitlement reforms and revenue increases from limiting deductions. But both of those ideas are unpopular too.

According to a new Quinnipiac poll, 70 percent of Americans oppose cuts to Medicaid and 51 percent oppose raising the Medicare eligibility age. And a recent Washington Post-ABC News poll actually showed that second figure significantly higher, at 67 percent.

When it comes to limiting deductions, the WaPo-ABC poll showed opposition was stronger than support, 49 percent to 44 percent. As for specific deductions, Quinnipiac shows 67 percent oppose getting rid of the mortgage interest deduction (though just 28 percent are opposed if you limit it to the first $500,000 of the mortgage).

To be clear: These are not all the entitlement reforms and deductions being talked about, but they are among the most talked-about.

Republicans will note that the Q poll says people generally prefer limiting deductions as an alternative to raising tax rates (45 percent to 39 percent). But when you start talking about specific deductions that normal people enjoy, like the mortgage interest deduction, and compare that to raising taxes on the wealthy, the alternative doesn't look so great.

If and when the discussion begins to turn to specific deductions, it will become clear that it's much easier to talk about it as a broad goal than actually pick the deductions to eliminate.

3. Americans trust President Obama and the Democrats more

This Q poll says it all. Obama's approval rating is up to 53 percent, while Democrats in Congress have a 37 percent approval rating. The latter number might not seem good, but it is compared to the GOP's anemic 23 percent approval rating. Republicans in Congress don't even get the approval of a majority of their own party, with 47 percent of Republicans approving of the congressional GOP and 43 percent disapproving.

A few other numbers: While 56 percent think Obama and the Democrats will make a good faith effort on the fiscal cliff, just 43 percent think Republicans will, and matched up against one another, people trust Obama and the Democrats over the Republicans by a 53 percent to 36 percent margin. And the WaPo-ABC poll showed twice as many people would blame the GOP as blame Democrats if the fiscal cliff is breached.

The one major area where Republicans have a consistent edge in polling when it comes to the fiscal cliff talks is their reputation for cutting spending, which Americans really like and which Republicans would be wise to emphasize more as the debate lingers on. (There has also been some suggestion that the Alternative Minimum Tax could help the GOP.)

To this point, though, that point has gotten lost as the debate has focused much more on the issues where the GOP has very little leverage.

It's all a recipe for Democrats to get much more of what they want out of the fiscal cliff deal.