Bank of America's $21bn acquisition of ABN Amro's US division has hit a potential stumbling block after two US senators requested assurances over potential job cuts and community involvement at the Chicago-based LaSalle.

Barack Obama, the presidential hopeful, and Senate whip Dick Durbin asked to meet Ken Lewis, BofA chief executive, to discuss a transaction that would eliminate the city's last major bank headquarters and lead to at least 4,000 job losses.