"False pretenses" refers to a situation where someone deliberately lies or misrepresents themselves in order to deceive or trick others into believing something that is not true. Full definition
I spent altogether too much time on political sites, arguing with these supporters, especially of the thistle - headed ignoramus who got elected under false pretenses by morons. (sbnation.com)
W invaded a country on false pretenses while bankrupting our economy. (religion.blogs.cnn.com)
But I think an «obtaining money by false pretenses» lawsuit is getting closer every day. (religion.blogs.cnn.com)