(CNN) News broke Friday morning that preliminary conversations have begun about the possibility of Ohio Gov. John Kasich (R) and Colorado Gov. John Hickenlooper (D) running as a unity ticket for president in 2020.

"The idea of a joint ticket has been discussed, but not at an organizational or planning level," a source familiar with the discussions told CNN's Mark Preston Friday . "What they are trying to show the country is that honorable people can disagree, but you can still problem solve together. It happens in businesses and it happens in families. Why can't it happen in Washington?"

On its face, the idea has obvious appeals. People are sick of the two-party system and desperate for an alternative option. Kasich and Hickenlooper are pragmatists more than they are ideologues. And they both happen to come from swing states in a presidential general election.

But like almost everything in life, the joint Kasich-Hickenlooper ticket looks better on paper than it likely would be in practice. Here are five reasons to be skeptical.

1. Most people are partisan

Yes, I know that the fastest-growing group of voters in recent years is independents or those with no party affiliation, and poll after poll suggests people believe now more than ever that the two-party system doesn't serve them well.

But the truth is that -- at heart -- most people are either a Democrat or a Republican. ( This study of independents by the Washington Post and the Kaiser Family Foundation is totally fascinating and makes that point well.) Lots and lots people identify as "independent" -- because they like the idea of being open-minded -- but always vote for one party or the other.

As The Washington Post's Philip Bump wrote in 2016 : "People may consistently vote for Republicans, but they would rather call themselves 'independents.' There's an appeal to being an outsider and to outsider politics that's reflected in how people see themselves."

2. The two-party system is deeply entrenched

There's a reason that the last third-party candidacy to have any real impact was Ross Perot in 1996. (And, if we're being honest, it was really Perot in 1992.) It's very, very hard to run for president outside the two-party system. For all the problems people have with the two major parties -- including partisans who identify with one side or the other -- the reality is that the parties do lots and lots of the dirty work that is incredibly time-consuming and expensive.

Ensuring that the party's presidential nominee gets on the ballot in every state -- each state has different rules for how you do so -- is a little-known but important part of party organizations. Ditto the painstaking and hugely costly process of identifying and contacting voters. And there are a thousand other small (and large) tasks that the two parties handle without the nominee ever knowing.

The only way you can hope to match that sort of organizational know-how is with lots of money. (See Perot, Ross.) Which brings me to...

3. The money problem

The post-Watergate public campaign financing system is dead. ( Barack Obama circa 2008 killed it. ) Which means that unless you are as famous and ubiquitous as Donald Trump -- neither Kasich nor Hickenlooper are -- you need, at a minimum, $1 billion to run a competitive race for president in 2020.

Unlike the two parties, which have dedicated major donors who have been conditioned over the years to cut big checks to the party committees and its candidates, there's no such structure for an independent bid. And it's not at all clear to me that major Democratic or Republican donors will abandon their party to donate big dollars to a bipartisan ticket.

Even if you assume that Kasich and Hickenlooper would gets loads of free press if they ran as independents for president -- and they would -- the duo would still need to raise north of $500 million (and, really, north of $750 million) to stay within shouting distance of the two major party nominees. It's hard to see a path where they get to that number.

4. Democratic pressure on Hickenlooper

Potential 2020 Democrats are already lining up for the chance to run against Trump. He has the lowest approval ratings at this point in a presidency ever. He, on an almost daily basis, antagonizes a Republican member of Congress or a key constituency.

In short: The Democratic nomination in 2020 looks very much like a nomination worth having.

If Trump stays anywhere near as unpopular as he currently is, there will be huge pressure on Hickenlooper to stay away from any sort of unity ticket that could jeopardize Democrats' clear shot at Trump. The party leadership would lean on every major Democratic donor to keep money away from Kasich/Hickenlooper. And the Colorado governor would be made a pariah by the activist left.

5. A Trump second term

The one thing uniting everyone who might be a potential Kasich/Hickenlopper voter is their distaste for Trump and the desire to keep him from a second term. Which is a problem given that any back-of-the-envelope calculation makes clear that a serious third-party candidacy would make it more likely that Trump can win do just that.

Given Trump's current poll standing -- with the massive caveat that he isn't up for reelection for more than three years -- it's very hard to imagine him winning a two-way race for a second term. But, if there was a third-party ticket siphoning off, say 15 to 20% of the national vote, Trump's path to reelection becomes more plausible.

Unless and until Kasich/Hickenlooper could prove that they were going to be more than just a spoiler, it's hard to see a movement building behind them.