From what I understand Rush Limbaugh and some other conservatives are predicting this. Their assessment is that soon the Democrats will see and realize that their current group of candidates are beyond being elected over Donald Trump due to their totally outrageous and socialistic views and policies and after all the debates and before the convention another candidate will swoop in and be drafted by the party provided she is willing.
I too believe this is a very reasonable assessment and quite likely to win the White House for the Democrats so if this does happen then whatever money you have in stocks be prepared for a massive drop in the stock market. Under Trump it's seen (the Stock Market that is) a historic rise but under a Democrat, if elected, then the market will see a huge massive drop because most likely they know what will happen if a Democrat is elected and most likely our economy will also likewise tank. Many though will be happy and satisfied if this happens because Donald Trump will be gone and vanquished from the White House.
It's really amazing just how many people, today, wish for complete failure and disaster in hopes that such would mean political death for Donald Trump.