And they're off... but who's going to win Westminster race?
We won't know all the candidates until nominations close in a week's time but it is already clear that this could be one of the toughest elections to predict and fight in the history of Northern Ireland.
Parties are so tightly bunched in some constituencies that it would take very little to upset predictions. Between now and the deadline, smaller parties may enter the race with an unknown effect. The TUV, for instance, are rumoured to be running in Fermanagh South Tyrone where the DUP and UUP are both supporting UUP veteran Tom Elliott.
Several constituancies are highly predictable. It would, as the saying goes, be a major upset if West Belfast, East Antrim, East Londonderry, Lagan Valley, Mid Ulster, North Antrim, North Down, South Down, Strangford or West Tyrone changed hands. Major upsets do happen, one came in East Belfast last time, but they are rare.
The rest could conceivably change hands, four of them covered by a unionist pact. The most important is East Belfast where, without an Ulster Unionist opponent, Gavin Robinson is favoured to take the seat off Alliance's Naomi Long - but it is not in the bag yet. If Ms Long does lose it will deprive Alliance of parliamentary presence, allowances and status, so this will be a fierce contest. In North Belfast the DUP were worried enough about the future of their MP Nigel Dodds, now regarded as a likely next leader, to include it in the deal. Now Mr Dodds' future appears secure.
In return the UUP got a "clear run" in Newry and Armagh and in Fermanagh South Tyrone (FST) but in reality only the second of these seats is even a remote prospect. There is however nervousness that another unionist may nominate in FST before next week's deadline.
South Antrim, where there is no deal and it was a close run last time, may be the UUP's best chance, but it would take luck to unseat the DUP's Willie McCrea.
Sinn Fein fancies its chances in Foyle against Mark Durkan, the former SDLP leader, but so far Mr Durkan is still favourite. He will need votes from both unionists and anti-Sinn Fein nationalists to do so and he usually gets them.
That leaves Upper Bann and South Belfast which are both unpredictable. In Upper Bann the 2011 Assembly vote split more or less evenly between the DUP and Sinn Fein, with the UUP about three points behind. The DUP will be playing up the fact that a strong vote for Ms Dobson could be at Mr Simpson's expense and could let Cat Seeley of Sinn Fein in. That would be an unexpected outcome but it will be watched.
South Belfast is really interesting. The SDLP's Dr Alasdair McDonnell has defied gravity by holding what was traditionally a unionist seat since 2005. Last time Sinn Fein withdrew but this time he faces tough opposition from Mairtin O Muilleoir, the former Lord Mayor.
There is no unionist pact though so the UUP's Rodney McCune, a young barrister who most recently worked for the party as a special adviser, and Jonathan Bell of the DUP are both standing. In this constituency the DUP strung the UUP along, delaying the announcement of Mr McCune as a candidate, spiking his campaign to some extent. He is now fighting hard to make up ground.
A liberal on most social issues, like gay marriage, and Labour-leaning in his personal politics, Mr McCune will be a threat to Alliance's Paula Bradshaw as much as to Mr Bell or Dr McDonnell. He is an interesting candidate but will need this election just to establish himself.
Dr McDonnell has the incumbency factor on his side and he should hold the seat again if all goes well. However, it is still a long time to the election and he is vulnerable to events until the votes are in.
If Dr McDonnell (now 65) does lose it looks like Jonathan Bell, the junior minister. If he doesn't make it, Mr Bell, now 45 and representing Strangford as an MLA, is likely to be kept in this constituency to have another crack at it next time.