WASHINGTON (Reuters) - Making a final push toward the crucial Super Tuesday vote, Super PACs backing Republican presidential candidate Ted Cruz bought $2.4 million in advertising supporting him in eight states, the groups told Reuters.  The ads purchased by Keep The Promise and its various offshoots include radio, television and online and are the latest effort by supporters of Cruz, a U.S. senator of Texas, to dislodge Donald Trump from the front-runner position in Tuesday’s critical 11-state Republican nominating contests. Should Trump sweep the contests, it could make stopping his path to the Republican nomination impossible. The outside groups supporting the presidential candidates have already spent more than $5.5 million on advertising in Super Tuesday states, according to analysis by Reuters of the spending reports filed with Federal Election Commission as of Friday morning.  Super PACs are permitted to raise unlimited amounts of money from individuals and corporations, but are prohibited from coordinating with the campaigns they are supporting. Most of the Super PACs have been used to fund expensive advertising budgets, while the campaigns themselves are responsible for staff and ground organization. Cruz’s backers are hopeful the ads will pull him ahead of Trump. Cruz is locked in a tight battle in his home state of Texas, where 155 delegates to be sent to the Republican National Convention are at stake, out of almost 600 delegates total in the states voting on Super Tuesday.  “On Super Tuesday, voters can both send a message to Washington AND send a serious, proven conservative to the White House by voting for Cruz,” said Kellyanne Conway, president of Keep the Promise I, one of the groups backing Cruz. The groups spent $393,500 on radio ads in seven states. They also purchased more than $990,0000 in television ads that will run in Georgia, Alabama, Tennessee, Arkansas and Oklahoma - the most crucial states for Cruz to narrow the margins with Trump.  The groups also spent $1 million on digital ads in eight states, including Minnesota, where so far none of the outside groups have bought advertising.  (Reporting by Ginger Gibson; Editing by Leslie Adler) This article was funded in part by SAP. It was independently created by the Reuters editorial staff. SAP had no editorial involvement in its creation or production.