That explains recent speculation about a multi-coloured rainbow alliance voting with David Cameron and company to cut the Commons down to size - an alliance that would probably have to include unionists, nationalists, independents and a Green.
The European Parliament demanded further negotiations on the EU's multi-year budget, with MEPs voting earlier this week that they would only accept the deal on certain conditions.
Congress can also threaten down the line to take out their frustration on what's called emergency supplemental bills, voting against the multi-billion dollar packages that literally fund the war.