By Peter Maushagen and Alastair Macdonald
STRASBOURG (Reuters) - When Emmanuel Macron speaks to the European Parliament on Tuesday many in Strasbourg may be listening less to his ambitions for a stronger European Union than for hints on how he may shake up their own party system.
Swept to power a year ago on the back of a party he created, the 40-year-old French president lacks clout in the EU legislature, where some of his grand plans may stand or fall, because his En Marche (Forward) movement still has no formal representation there. But that should change in EU-wide elections next year.
Some EU lawmakers and officials can see a major overhaul of alliances that may give Macron the kind of influence that German Chancellor Angela Merkel has through her conservative alliance.
"Europe would benefit democratically from a political recomposition," Macron said two months ago, saying he hoped that would come about after the European elections in late May 2019.
Several sitting French MEPs rallied to Macron's party, also known by its acronym LREM, as it secured a majority in the French assembly after he beat established left and right candidates on a pro-EU centrist platform and then saw off far-right nationalist Marine Le Pen in a runoff for the presidency.
But LREM has resisted joining one of the existing alliances which dominate access to funds and committee-room influence in the European Parliament. It has set its sights on entering the legislature in force next year. A new, LREM-led bloc could then help Macron defend his integrationist agenda for the Union.
Merkel's Christian Democrats, who share much of Macron's enthusiasm for a stronger EU but are wary of some of what Paris wants, hold sway in the centre-right European People's Party.
The EPP's informal cooperation with the Socialists and Democrats, mirroring Merkel's "grand coalition" in Berlin, has held a majority in a chamber where those hostile to the EU or to deeper integration can hope to increase their vote next year.
"CAT AMONG PIGEONS"
Aides to the president say he has yet to decide how LREM should operate in the EU. They say he will not go into detail on the party issue when he speaks on Tuesday morning to urge Europeans not to miss an urgent opportunity to strengthen cooperation as the long-sceptical British leave the bloc next March.
But with many in Parliament already contemplating reelection campaigns, Macron's calculations are very much on their minds.
"He put the cat among the pigeons," a senior parliamentary official told Reuters. "After the election, we will see a lot of merger and acquisition activity among parties in Parliament."
Aside from the EPP and S&D, which account for 56 percent of seats in today's 751-seat chamber, there are six other groups.
These must have at least 25 members from at least a quarter of the 27 member states. There are two far-right groups, one from the hard left, one on the right dominated by the British Conservatives and Poland's ruling party and two large groups near the center, the Greens and the liberals of ALDE.
This last group, led by the outspokenly federalist former Belgian premier Guy Verhofstadt, has courted LREM. Verhofstadt attended an LREM campaign event in Brussels this month, telling Reuters he planned to attend more. But he dismissed a question on whether LREM would join ALDE as "old politics".
"We must build alternatives to the old parties - the EPP and the S&D," he said, adding he shared Macron's "vision of Europe".
Aides to Macron stress he has made no decisions on whether, how or when to try and join forces in Brussels and Strasbourg: "En Marche is making contacts with parties who think the same," one said. "For the moment, it's a European networking effort."
The EPP, with no British seats to lose, is favorite to be the biggest party in a Brexit-diminished, 705-seat chamber, well ahead of an S&D shorn of UK Labour and hit by collapses in centre-left support in Germany, France and Italy.
ALDE currently has only 68 seats. But Macron, building on a big share of France's 79 seats, might target second, or even top the EPP, if he pulls in individuals or other national parties.
Macron aides play down suggestions LREM might foster new national counterparts across Europe - though they have been in contact with some new movements which share their ideas.
Lawmakers speculate that a strong showing from Spain's new Ciudadanos movement, already part of ALDE, could bolster Macron, while there is also talk of many from Italy's struggling centre-left Democratic Party shifting their EU allegiance.
Rome's buoyant 5-Star movement, revising former eurosceptic leanings, has already flirted with joining ALDE as it looks to ditch its moribund alliance with Britain's anti-EU UKIP.
Prediction is hard. Uneasy alliances are the rule in the EU legislature and party discipline is weak. Not all those now in ALDE share Macron and Verhofstadt's vision of a stronger federal Union - for example, Germany's newly eurosceptic Free Democrats.
Macron is assured a warm welcome from most in Strasbourg for his commitment to the Union. But his arrival also brings unease.
"The established parties are mad with worry," said Nicolai von Ondarza at Berlin's SWP think-tank, highlighting the role of pan-EU parties in next year's bargaining over top EU posts such as head of the EU executive. "Macron's new movement could become a power player and tip the scales on the filling of jobs."
(Additional reporting by Michel Rose in Paris, Writing by Alastair Macdonald, Editing by William Maclean)