National parties in the newly elected European Parliament line up in pan-EU groups.
These are in some flux following the vote, especially on the eurosceptic right, but in the outgoing legislature the eight groups were:
European People's Party (EPP - 180 seats in new legislature)
Lead candidate: Manfred Weber (Germany) EPP parliamentary leader
Centre-right: Favours free trade and business
Notables: German Chancellor Angela Merkel; outgoing European Commission chief Jean-Claude Juncker; Italian ex-premier Silvio Berlusconi; Polish EU summit chair Donald Tusk; Hungarian leader Viktor Orban, who is at risk of being expelled for anti-EU nationalism.
Socialists and Democrats (S&D - 146 seats)
Lead candidate: Frans Timmermans (Netherlands), deputy head of European Commission, former foreign minister
Centre-left: Favours worker’s rights, minimum corporate tax
Notables: Spanish Prime Minister Pedro Sanchez; Italian ex-premier Matteo Renzi; Swedish and Portuguese premiers.
Alliance of Liberals and Democrats (ALDE- 109 seats)
Lead candidates: Margrethe Vestager (Denmark), EU antitrust commissioner, former economy minister; Guy Verhofstadt (Belgium), ALDE leader, former prime minister
Liberal center: Favours free trade, stronger EU integration
Notables: French President Emmanuel Macron, though he is yet to formally link to ALDE; Dutch Prime Minister Mark Rutte; premiers of Belgium, Denmark, Finland, Luxembourg, Estonia
Greens (69 seats)
Lead candidates: Ska Keller (Germany) MEP since 2009; Bas Eickhout (Netherlands) MEP since 2009
Ecology: Left-leaning, seeks clean energy and environment
Notables: No national leaders; EU party leader, veteran Belgian MEP Philippe Lamberts; one high-profile government figure was Joschka Fischer, German foreign minister 1998-2005.
European Conservatives and Reformers (ECR - 59 seats)
Lead candidate: Jan Zahradil (Czech Republic), MEP since 2004.
Eurosceptic: Founded in 2009 when British Conservative leader David Cameron quit EPP to oppose deeper EU integration.
Notables: Polish ruling party leader Jaroslaw Kaczynski; Flemish nationalist N-VA leader Bart de Wever; Jimmie Akesson of anti-immigration Sweden Democrats; and – for this week at least – British Prime Minister Theresa May.
Europe of Nations and Freedom (ENF - 58 seats)
Lead candidate: No lead candidate; expect group to reshuffle after election.
Anti-immigration: Founded in 2015 by French National Rally’s Marine Le Pen and Dutch Freedom Party’s Geert Wilders.
Other notables: Matteo Salvini, Italian deputy premier from The League, biggest far-right party in new Parliament.
Europe of Freedom and Direct Democracy (EFDD - 54 seats)
Lead candidate: No lead candidate; expect group to reshuffle after election.
Anti-EU: Formed in 2014 by Nigel Farage, then-leader of UK Independence Party, now of the Brexit Party; key ally Italy’s 5-Star expected to shift to more centrist group after election.
Other notables: Italian deputy premier Luigi Di Maio of 5-Star; Joerg Meuthen, co-leader of Alternative for Germany.
European United Left (GUE - 39)
Lead candidates: Nico Cue (Belgium), trade union leader; Violeta Tomic (Slovenia), parliamentarian.
Far left: Anti-austerity, want more spending, trade control.
Notables: Greek Prime Minister Alexis Tsipras.