I see this idea from time to time here on the Great Orange. Folks opine that there's no real difference between the two big parties, and that we need an alternative to the Democrats. I don't blame you for voting 3rd party as a protest vote. Sometimes there isn't much difference (or not enough) between the two major party candidates. Marking the oval for "Green" or "Libertarian" does no harm in these cases.
First, though, make certain there really isn't much difference. Bush-Gore 2000, anyone? Nobel PP Laureate Al Gore versus serial warmonger Dubya? As it turned out, there was a HUGE difference. And so take great care in close races before going 3P.
Forming a new 3rd party and expecting that new party to help achieve a more progressive government, though, is utter folly. And I will relate that folly to patents under the fold.
Once upon a time I heard a discussion on NPR of the difficulties of being an inventor and bringing your new product to market. One difficulty that stuck in my memory, because they were so matter of fact about it, was this:
If your invention is really good, your patent will be broken.
Emphasis on the "will". Not maybe. Not "take these precautions". If your invention is worth $10M, it is worth $2M to some company already working in that field to break your patent - and you don't have $2M to fight back. They will wear you down; they will outlast you; your patent will be broken. In this case, you need to find a "white knight" - a rival to the attacking corporation, who will buy your patent from you and defend it. You have no hope of victory in the courts.
In the same way, a third party (let's call it the Progressive Party, or PP) which started gaining traction will be corrupted. Not maybe. It will be corrupted.
First, there is the simple matter of establishing a presence. Remember the Reform Party? Ross Perot founded that, funded it with millions of dollars, and ... where is it now? No seats in Congress, and since 1998 and Jesse Ventura no wins in governors mansions.
So, how will you build an PP infrastructure where you can compete in enough races to make a difference? Where will this money come from? Where will your volunteers come from?
Overcome that hurdle somehow. Now is when your fail becomes epic. How do you enforce purity among your candidates? Suppose Warren Buffet wants to run for Nebraska Senate on the Progressive Party slot. He's not really progressive - but he can self fund, and he has huge name recognition. How do you prevent the Nebraska PP from allowing Buffet to run? How do you prevent him from winning a primary or a caucus?
What keeps the PP from being a vehicle for the ambitious or vain (just as the Democrats and Republicans sometimes are) and running impure candidates?
Overcome that hurdle somehow. Your fail now becomes epochal. Do you recall the special election in NY-23? The Conservative (3rd party) candidate split the vote with the Republican, and a Democrat won the seat for the first time since the Civil War.
Consider that in 2010 there was an attempt made by Michigan Democrats to set up a phony Tea Party. Exactly how will you prevent the Kochtopus from supplying you with enough money to drain votes from the Democrats, but not enough to win? How do you avoid being used to elect Republicans? Perhaps you truly see no difference between Democrats and Republicans - but I assure you that the Republicans do see such a difference, and they will exploit you at every opportunity. Perhaps you will insist that PP candidates take no money from PACS and corporations and so on; very well, how do you propose to keep the Kochtopus from buying air time and running ads in favor of your candidate - just enough ads, mind, that you don't actually win?
Overcome that hurdle somehow. Your fail now becomes eternal. Because, you see, Barack Obama and Harry Reid and Nancy Pelosi and so on, so far as I can tell, didn't go into politics intending to become tools of the plutocracy. Most politicians, even Republicans, started out intending to help people by their lights. No one wants to be a tool. These are, by and large, people who entered politics as people just as ethical, moral, smart, and wise as you are or I am. And the system got a grip on them, and molded them and shaped them. Suppose that you manage to elect PP candidates to high office. What protects them from the system that has eaten so many souls? What keeps them from listening to lobbyists? What keeps them from following the polls? What keeps them from caring what is said about them on the local news, or by the Serious People in Washington? How do you propose to keep your good people good?
There is a glimmer of hope, and that is election reforms.
Suppose we could overturn Citizens United.
And we got public financing of campaigns.
And we got nationwide adaptation of the idea of a single primary for all candidates of all parties, with the top two candidates moving on to the general.
And perhaps we got the number of Congressional seats increased from 435 to 1305 (or some other larger number).
Given all that, there'd be some hope for the glorious Progressive Party to elect some people to Congress who would remain "true" progressives. But until then - no way. Starting a 3rd party is destined to fail until systemic change is achieved, and that change will come from the bottom up, not from the Federal government down.