US President Barack Obama made one last plea today for lawmakers to approve a massive overhaul of the country's health care system when they take an "historic" vote on his top domestic priority this weekend, dpa reported. The culmination of more than a year of often bitter debate, the House of Representatives is likely to vote Sunday on a package of reforms aimed at extending coverage to more than 30 million Americans that lack health insurance. Both supporters and opponents left no doubt about the importance of Sunday's expected vote in the House and were engaged in last-gasp efforts on Friday to rally their side. "We are going to do something historic this weekend. That's what this health care vote's all about," Obama said at a campaign-style event at George Mason University in Virginia. The outcome of Sunday's landmark vote remains uncertain, with Republicans united in opposition and many moderate Democrats also wavering over whether to support the controversial health reforms, which are estimated to cost 940 billion dollars over 10 years. "The American people do not want any part of this," John Boehner, the top Republican in the House, told reporters. "If anyone thinks the American people are going to forget this vote, just watch." Sunday will not be the final step in the long-running health saga. The House will be voting on health legislation that was approved by the Senate late last year, but will also adopt a round of changes to the bill which will have to go back to the Senate for final approval.