Political parties attempt to influence government by electing members to office to control government, whereas interest groups seek to influence policy on specific issues. Political parties are connected to voters and get their power from being elected. There are arguments that the US would benefit from stronger parties that provide clear choices to voters. The US has historically had a two-party system dominated by Democrats and Republicans, though other party systems occurred in the past. The electoral system of single-member districts and plurality voting provides incentives for just two major parties.