Prior to the 2016 election President Obama used his parseltongue to encourage illegal aliens to break federal law and vote in the presidential election:

Today, Donald Trump pointed out the illegal alien voting issue:

In addition to winning the Electoral College in a landslide, I won the popular vote if you deduct the millions of people who voted illegally — Donald J. Trump (@realDonaldTrump) November 27, 2016

According to a recent research study as many as 2.8 million illegal aliens voted in 2008 and 2012. Full pdf below:

[excerpt] …”How many non-citizen votes were likely cast in 2008? Taking the most conservative estimate (those who both said they voted and cast a veriﬁed vote) yields a conﬁdence interval based on sampling error between 0.2% and 2.8% for the portion of non-citizens participating in elections.

Taking the least conservative measure e at least one indicator showed that the respondent voted yields an estimate that between 7.9% and 14.7% percent of non-citizens voted in 2008.

Since the adult noncitizen population of the United States was roughly 19.4 million (CPS, 2011), the number of non-citizen voters (including both uncertainty based on normally distributed sampling error, and the various combinations of veriﬁed and reported voting) could range from just over 38,000 at the very minimum to nearly 2.8 million at the maximum”…