GUATEMALA CITY (Reuters) - Guatemala s Congress on Monday voted to preserve President Jimmy Morales s immunity from prosecution after the attorney general s office submitted a request to investigate him over suspected financing irregularities during his 2015 election campaign. Attorney general Thelma Aldana and a U.N. anti-graft body said last month they were seeking to investigate Morales over the illegal financing allegation. Two days later, Morales declared the head of the U.N. body  persona non grata.  Under the leadership of Ivan Velasquez, a veteran Colombian prosecutor, the CICIG has caused problems for Morales, first investigating his son and brother, and then seeking to prosecute him over some $800,000 in allegedly unexplained campaign funds. The Guatemalan president won office in 2015 running on a platform of honest governance after his predecessor, Otto Perez Molina, was forced to resign and imprisoned in a multi-million dollar graft case stemming from a CICIG investigation. Morales, a former comedian, has denied any wrongdoing. 