With the US Congress returning on Tuesday after a two-week break, leaders from both parties are preparing legislative agendas—on issues including the economy, Iraq and immigration—designed to present the three remaining White House candidates with dangerous political choices.The obstacle course begins immediately, with a Democratic-sponsored Senate vote on Tuesday on legislation to ease the mortgage crisis. Next week, Iraq will dominate, when General David H Petraeus and Ambassador Ryan C Crocker testify before two committees on which Senators John McCain, Hillary Rodham Clinton and Barack Obama serve.By the week of April 21, sweeping housing legislation could reach the House floor. By the end of the month, an Iraq war funding bill could be moving, with a second economic stimulus package attached.Republicans will counterpunch by pushing for a vote on tough immigration legislation and pressuring Democrats to cave in to their demands for terrorist surveillance legislation that offers retroactive legal immunity to telephone companies that cooperated with the Bush administration’s warrantless wiretapping efforts. It is clear that Capitol Hill will be a battleground for one of the longest presidential campaigns in the nation’s history. “A lot of what we’re thinking about is, A, what you’ve got to do to do the right thing, and, B, where the president is and where John McCain is,” said House Democratic Caucus Chairman Rahm Emanuel.There’s nothing new about using the congressional agenda as a staging ground for presidential campaign themes. In July 2004, just weeks before Senator John F. Kerry accepted his party’s nomination, Republicans forced a vote on an amendment to the Constitution that would have banned same-sex marriage, a proposal that was part of the close coordination of Senate GOP leaders and President Bush’s campaign team. Democrats say they hope to highlight some of McCain’s less popular positions by forcing him to vote on certain issues or take stands on the legislation from the trail, as Kerry was in 2004.A test vote comes on Tuesday when the Senate moves to take up legislation that would grant bankruptcy judges more authority to modify mortgages, provide $200 million for mortgage counselling, authorise state housing agencies to float revenue bonds for the purchase of homes in foreclosure and allow homebuilders to write off more losses from their taxes.Iraq is a more complicated political issue. When they discuss Iraq, Republicans and Democrats seem to be looking at two different wars. To Democrats and their backers, the recent increase in sectarian violence is proof that Bush’s troop increases more than a year ago have failed to calm the country or foster political and ethnic reconciliation. To Republicans, the fighting between Iraqi government forces and Shiite militias proves the point that the central government is making progress. But Democratic leaders made it clear on Monday that their main focus will remain the economy.