Over the past several years, a "Movement for a People's Party" has gained some traction in the US. As it seems to be a popular-front-type initiative, its attitude towards existing non-Republican-and-Democratic parties is problematic: If the MPP treats existing parties (say, the Green party) competitively, it is likely to distance members and supporters of those parties; but if it doesn't, it risks being "yet another third party" among the plethora of others.
What, therefore, has been the actual approach and the official position of the MPP regarding engagement with existing parties? More specifically, have they discussed the prospects of inter-party factions or caucuses so that existing parties can enter the MPP as organizations?