WASHINGTON - (AP) - Defiant and frustrated, President Barack Obama aggressively challenged Republicans Thursday to get behind his jobs plan or explain why not, declaring that if Congress fails to act "the American people will run them out of town." The president used a White House news conference to attempt toheighten the pressure he's sought to create on the GOP by travelingaround the country, into swing states and onto the home turf of keyRepublican foes including House Speaker John Boehner and Texas Gov.Rick Perry.Giving a bit of ground on his own plan, he endorsed a newproposal by Senate Democrats to tax millionaires to pay for hisjobs program. "This is not a game," he said. Obama made no apologies for his decision to abandon seekingcompromise with Republicans in favor of assailing them, sometimesby name. He contended that he'd gone out of his way to try to workwith the GOP since becoming president, reaching hard-fought dealsto raise the government's borrowing limit and avert a governmentshutdown, and had gotten nothing in return."Each time, we have seen game playing," the president said."I am always open to negotiations. What is also true is they needto do something."He predicted dire political consequences for his opponents ifthey don't go along."I think the American people will run them out of town becausethey are frustrated and they know we need to do something big."Yet Obama's campaign has not swayed Capitol Hill Republicans whooppose the higher taxes he and other Democrats want to use to payfor his proposal. They accuse Obama of playing "campaigner inchief" instead of working with them."If the goal is to create jobs, then why are we even talkingabout tax hikes?" Senate Minority leader Mitch McConnell, R-Ky.,said Thursday.Republicans are resolutely opposed to much of Obama's jobsinitiative, both for its tax increases for wealthier people andsmall businesses and its reprise of stimulus spending on roads,bridges and schools and grants to local governments to pay thesalaries of teachers and first responders. They criticize his billas another version of his $825 billion stimulus of 2009, one thatthis time would rely on raising taxes.Obama did say he would support a new approach by SenateDemocrats for paying for his jobs bill with a tax on millionairesrather than his plan to raise taxes on couples making more than$250,000. The president's strident tone underscored a difficult politicalpredicament as he seeks re-election with the economy slowing andunemployment stuck above 9 percent. "Our economy really needs ajolt right now," he said.The president said that without his nearly $450 billion packageof tax cuts and public works spending there will be fewer jobs andweaker growth. He said the bill could guard against anothereconomic downturn if the situation in debt-laden Europe worsens.With the plan expected to come up for debate in the Senate nextweek, he urged every senator to think "long and hard about what'sat stake." "If it turns out that Republicans are opposed to the bill, theyneed to explain to me, and mostly importantly their constituents,what they would do," Obama said. "What I've done over the last several weeks is take the case tothe American people so they know what is going on." Obama said the economy is weaker now than at the beginning ofthe year. Citing economists' estimates, he said his $447 billionjobs bill would help the economy grow by 2 percent and create 1.9million jobs. "At a time when people are having such a hard time, we need tohave an approach that is big enough to meet the moment," he said.Obama addressed the disaffection with politics pervasive amongthe public that's driven down his approval ratings - and even moreso, Congress' - as he seeks a second term.Appearing fed up, Obama blamed it on Republicans who he saidrefuse to cooperate with him even on issues where he said they onceagreed with him. He talked about the ugly debate over raising thegovernment's borrowing limit that consumed Capitol Hill and theWhite House over the summer, until Obama gave in to Republicandemands for deep spending cuts without new taxes."They don't get a sense that folks in this town are looking fortheir best interests," Obama said of Americans in general. "So ifthey see that over and over again, that cynicism is not going to beproven wrong unless Congress does something different.""What the American people saw is that Congress just didn'tcare." Obama also said the "Occupy Wall Street" demonstratorsprotesting against Wall Street and economic inequality areexpressing the frustrations of the American public. He said he understands the public's concerns about how thenation's financial system works. And he said Americans see WallStreet as an example of the financial industry not always followingthe rules.