WASHINGTON (Reuters) – President Barack Obama will seek to build momentum for US immigration reform this week ahead of his State of the Union address, which is expected to challenge Republicans to take up an overhaul amid an increasingly contentious debate in Washington. Obama plans to hold a series of White House meetings with corporate chief executives, labour leaders and progressives today to lobby for their support, and he has dispatched Homeland Security Secretary Janet Napolitano to the Southwest to tout the administration’s border security efforts. The flurry of activity, including new moves in Congress, comes amid disagreement between the Democratic president and many Republicans over the question of citizenship for illegal immigrants, an obstacle that could make it hard to reach a final deal on sweeping legislation. House Majority Leader Eric Cantor, the second-ranking Republican in the House of Representatives, will address immigration reform and other issues in a speech today to the conservative American Enterprise Institute.