How are the seats distributed in Congress and the Senate?

The upcoming elections on November 29 feature significant changes in party alliances for the Congress and Senate in Spain. The distribution of seats in both chambers is determined by the number of representatives allocated per constituency. In the Congress, the left-wing coalition, Frente Amplio, led by Ada Colau, has formed various alliances, while Podemos integrates with other leftist parties in specific regions. In the Senate, a coalition of PSOE, Frente Amplio, and other leftist forces competes against a joint effort from PP and Vox, with both parties strategically withdrawing from certain provinces to optimize their electoral chances. Vox's strategy includes placing independent candidates on PP lists in regions where they are not running.