US President Barack Obama on Friday branded Republicans as extreme and reactionary, in campaign appearances for high-profile Democratic senators under threat in November's mid-term polls.
Obama rallied crowds in Los Angeles, California, and was to move on to gambling paradise Nevada in a bid to rescue wobbling Democratic Senate majority leader Harry Reid, on the third day of a four-day campaign blitz.
He charged that the first Republican president, his political hero Abraham Lincoln would not be able to win the opposition party's presidential nomination in the modern age.
"Seriously, can you imagine him trying to run with these folks?" Obama said, in a bid to portray the Republican Party as outside the mainstream ahead of November 2 congressional polls in which his Democrats fear heavy losses.
Obama accused Republicans of sitting on their hands while he saved the economy from a second Great Depression
and of wanting to go back to the same lax regulatory regimes that caused the crisis in the first place.
"This agenda that poses as conservatism is not conservative. It resulted in a radical shift from record surpluses to record deficits, allowed Wall Street to run wild, nearly destroyed our economy," Obama said.
"This is a choice between the past and the future, between fear and hope, between moving backwards and moving forwards. And I don't know about you, but I want to move forward," Obama said, at a campaign event for under-fire Democratic Senator Barbara Boxer.
"They are clinging to the same worn-out, tired, snake-oil ideas that they were peddling before."
Republicans need to win 39 seats to take back the House after four years of Democratic control -- a task well within their reach with some analysts judging up to 90 races in the 435-seat chamber as competitive.
In the Senate, Republicans need a 10-seat swing, a result that may be beyond them after several races tightened in favor of Democrats in recent days, and a scenario of six or seven seats changing hands seems more likely.