The European political parties are essentially vehicles to enable MEPs to operate procedurally in the European Parliament, only loosely held together by ideology. (The most ideological MEPs - the Euro-sceptic far right - tend to find it the most difficult to form lasting alliances.) We should not be terribly surprised by this. Political parties, in the end, are tactical alliances of individual party members who want to see the world changed in a particular way. They often like to behave as if they are monolithic bodies, but this is rarely the case. In the European Parliament, given the vastly different political bases from which its member sderive support, it is almost surprising that ideology plays as big a role as it does.
There have historically been about half a dozen party groups in the European Parliament: the two big ones are the centre-left Social Democrats, and the centre-right European Peoples Party (Christian Democrats for the most part). Next in size, at present, are the Liberals, and some way behind them are the Communists, the Greens, and a couple of other right-wing groups, plus some MEPs who cannot or will not join larger groups.
Non-Irish readers (if any have got this far) may need reminding that Fianna Fáil, founded in 1926 by Éamon de Valera, has been the largest party in every Irish election since 1932 and indeed has been in government for 59 of the subsequent 79 years (winning again in 2007). They are in trouble at the moment, though, with latest polls putting them not just in second place to Fine Gael but within striking distance of the third-placed Labour Party.
The natural European partnership for Fianna Fáil was and probably still is with the largest block of centre-right political parties, the European People's Party. But Fine Gael managed to get membership in that grouping at an early stage, and (as the PD's later did with the liberals) were able to prevent Fianna Fáil from joining. Fianna Fáil's participation in Europe-wide politics then became to an extent a hostage of the internal politics of the Right in France and later Italy.
We have to backtrack a bit here. Originally, the French Gaullists had sat with the Liberal Group in the old unelected European Parliament. They split off to form their own faction, the European Democratic Union, in 1965, roughly at the time of the Empty Chair crisis. (Meanwhile, Alain Poher's Republicans were firmly integrated into the European People's Party, Poher himself being leader of both at the time, and they were able to block the Gaullists from membership just as FG have subsequently done with FF). The arrival of FF in the then unelected European Parliament in 1973 supplied the Gaullists with potential allies, and together they created a block called (with eerie prophetic resonance) the European Progressive Democrats.
After the first elections to the European Parliament in 1979, they were joined by Winnie Ewing of the Scottish Nationalist Party, and by a random Dane. In the 1984 elections, they lost the Dane but gained a few more French MEPs, and renamed themselves the European Democratic Alliance. In 1989 they picked up a splitter from the Greek Νέα Δημοκρατία, but lost Winnie Ewing (the SNP having jumped ship to the Rainbow Group / European Free Alliance which represented various regional parties). By 1995 they had absorbed Berlusconi's Forza Italia MEPs, two from a smaller Portuguese party (Partido Popular), and the nutcase Samaras Πολιτική Άνοιξη from Greece, and renamed themselves the Union for Europe.
But this was the height of their strength: Berlusconi took his lads to the European People's Party in 1998, having managed to persuade the other Italians already there not to block his membership. After the 1999 elections, the Gaullists followed Berlusconi into the EPP, having managed to smooth the way with their fellow French right-wingers. Again, because of Fine Gael, they could not bring FF with them.
FF and the Portuguese PP then formed another new group, the Union for a Europe of the Nations, and were joined by the post-fascist Alleanza Nazionale from Italy, and another random Dane (Samaras' nutcases having been meantime rejected by the Greek voters, though unfortunately Samaras himself has since returned to the European Parliament for Νέα Δημοκρατία).They didn't do too badly in the scramble for new members in 2004 - picking up two small Lithuanian parties, one larger Latvian one, and most importantly the Kaczyński twins' Prawo i Sprawiedliwość in Poland. Since then they have acquired three more Polish parties and two more Italian groups (the Lega Nord and a random Sicilian).
But it cannot be comfortable company for Fianna Fáil. It was all very well to be in with the Gaullists, but times have changed; when the two largest delegations in your group are the Italian post-fascists and the Kaczyński twins, you may want to start thinking about moving. In any case the alliance with the Gaullists and Berlusconi was really more a matter of style than of substance: these were strong right-wing parties with impeccable nationalist credentials set up by powerful leaders, and yet they felt that the Christian Democrats would suit them best.
In addition, the growing importance of the pan-European parties as political vehicles is starting to rub. At the height of his powers, Bertie Ahern was being talked about for one of the top EU jobs. Although that prospect seems much less likely today, the fact is that the internal dynamics of EU politics meant that no FF candidate could ever be a serious runner in the first place. FF's current political grouping is fourth in the pecking order, a long way behind the Liberals, who themselves are not exactly snapping at the heels of the Socialists or the EPP. Given that the Christian Democrats and Socialists are blocked for FF, the Liberals are the obvious next choice.
The Liberal group includes not only parties of the vaguely left-of-centre orientation of the British Lib Dems, but also numerous parties with their roots in free-market ideology such as the German FDP, and some other interesting minorities - Swedish-speaking Finns, the ethnic Turks of Bulgaria, the Catalonians. They also at present include independent Irish MEP Marian Harkin, a small-town politics candidate from Sligo. On FF's economic record, good and bad, they would fit as well with the Liberals as with the Christian Democrats (some of whose members are avowedly centrist rather than right-wing in orientation). In the European Parliament, if you want to be effective, it is easier to be a smaller fish in a bigger pond rather than a big fish in a small pond.
I referred earlier to the possible particular concerns of Alliance and Lib Dem members about FF's membership of ELDR. A few years ago I would have shared them. Fianna Fáil's traditional attitude to the Northern Ireland problem was not a liberal one. It was based firmly on Irish nationalism, as one would expect from a party with its origins. The Progressive Democrats, now defunct, split from Fianna Fáil at least partly on the Northern Ireland issue. But here again times have changed. The 1998 Agreement, negotiated by Fianna Fáil on the Irish government side, has punted the Northern Ireland problem into the long grass; Fianna Fáil successfully urged the replacement of Articles 2 and 3 of the constitution by referendum. While I still wouldn't vote for FF, it is clear that they have moved on from the days of Haughey. (And even in the old days, one would have to reflect that if the Ulster Unionists and British Conservatives can sit in the same group as Fine Gael, perhaps liberals can be as flexible.)
Don't get me wrong. I don't for a moment think that Fianna Fáil can reasonably be described as a liberal party as matters stand at the moment. Indeed, I think it's very likely that Fine Gael at some (probably rather distant) future date will drop their opposition and allow them to join the EPP - ELDR have suffered defections in that direction before, most notably the Portuguese PSD and Hungarian FIDESz. On the other hand, I can live with three or four or five FF MEPs swelling the Liberal ranks in the European Parliament; and who knows, the ideology may rub off on them?