In the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, the two major political parties, the Republicans

Republican Party (United States)

The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...

 and the Democrats

Democratic Party (United States)

The Democratic Party is one of two major contemporary political parties in the United States, along with the Republican Party. The party's socially liberal and progressive platform is largely considered center-left in the U.S. political spectrum. The party has the lengthiest record of continuous...

, are often referred to as "the two sides of the aisle".

Origin of the usage

Usage of the term "aisle" in this regard derives from the fact that in the United States Senate and the United States House of Representatives members' desks are arranged in the chamber in a semicircular pattern and the desks are divided by a wide central aisle.

By tradition, Democrats sit on the right of the centre aisle (as viewed from the presiding officer's chair) while Republicans sit on the left; oddly this is the exact opposite of the "left/right" political leanings of the parties themselves.

"Crossing the aisle"

A member of one party who votes for legislation supported by the other party and generally opposed by his own party is described as "crossing the aisle", i.e., "Five Democrats crossed the aisle and voted with the Republicans." In other countries operating under the Westminster system

Westminster System

The Westminster system is a democratic parliamentary system of government modelled after the politics of the United Kingdom. This term comes from the Palace of Westminster, the seat of the Parliament of the United Kingdom....

, a similar phrase is "crossing the floor

Crossing the floor

In politics, crossing the floor has two meanings referring to a change of allegiance in a Westminster system parliament.The term originates from the British House of Commons, which is configured with the Government and Opposition facing each other on rows of benches...

".

"Both sides of the aisle"

A proposed law that has bi-partisan

Bipartisanship

Bipartisanship is a political situation, usually in the context of a two-party system such as the United States, in which opposing political parties find common ground through compromise. The adjective bipartisan can refer to any bill, act, resolution, or other political act in which both of the...

support is said to be supported by "both sides of the aisle".