WASHINGTON (Reuters) - Republicans scaled back plans for deep cuts in US government spending as they took power in the House of Representatives on Wednesday, diluting a key promise that helped them to victory in Novembers election. A senior Republican also signalled the party could work with the administration of President Barack Obama, a Democrat, to avert a debt crisis in the coming months. Our spending has caught up with us, and our debt will soon eclipse the size of our entire economy. Hard work and tough decisions will be required, incoming House Speaker John Boehner said in excerpts of a speech due later in the day. Republicans control of the House and their larger minority in the Senate usher in a new era of divided government after their big election gains that were due mostly to voter anger at high unemployment and the large $1.3 trillion deficit. But Obamas Democrats still control the Senate and can block the Republican agenda, which includes a plan to repeal the presidents landmark healthcare reform and a crackdown on Wall Street. The incoming House budget chief, Republican Paul Ryan, told NBCs Today programme a Republican campaign promise to cut $100b in spending this year had been compromised by the momentum of spending already under way. The actual cuts put forward could be substantially less than $50b, a House Republican aide said, because the fiscal year will be halfway through by the time Republicans get a chance to affect spending. A deal on taxes in December showed that Obama and the opposition can work together but there are many thorny issues to deal with as the US recovers slowly from its worst recession since the 1930s. Bond markets fear political gridlock could prevent Congress from raising the level of debt the country can take, potentially making the US default on its debt. Bill Gross, manager of the worlds largest bond fund, warned that mindless US deficit spending could result in higher inflation, a weaker dollar and the eventual loss of Americas top-notch credit rating. The problem is that politicians and citizens alike have no clear vision of the costs of a seemingly perpetual trillion dollar annual deficit, said Gross, who oversees the $256b PIMCO Total Return Fund. As long as the stock market pulsates upward and job growth continues, there is an abiding conviction that all is well and that 'old normal norms have returned. Not likely. Ryan, the incoming House budget chief, said he will seek spending concessions from the Obama administration in exchange for any increase in the national debt ceiling. Im not interested in raising the debt ceiling on the hope that a promise will be fulfilled at a later time, Ryan told MSNBC. Im only interested in raising the debt ceiling if we get concessions on spending, on real controls to get our fiscal situation turned around and headed in the right direction. His comments suggested Republicans are willing to work with Obama on raising the debt level, although fights could still derail that before the issue comes to a head in March or April. The two parties are headed for their first big clash next week, when Republican House leaders plan a vote on repealing Obamas healthcare overhaul. The effort looks doomed to failure in the Democratic-led Senate but the vote could set the tone for a combative first few months. Outgoing Speaker Nancy Pelosi, in remarks prepared for delivery during the Houses opening day, said Congress should focus on what largely cost Democrats control of the chamber in Novembers election - the near double-digit jobless rate. Our most important job is to fight for American jobs. And so Democrats will judge what comes before Congress by whether it creates jobs, strengthens our middle class, and reduces the deficit - not burdening future generations with debt, she said.