Brussels is bracing for one of its biggest battles — the fight for cash in the EU's next long-term budget.

Budget Commissioner Günther Oettinger will present his proposal for the 2021-2027 Multiannual Financial Framework (MFF) on May 2 and aims to have final plans approved before the 2019 European Parliament election.

Veterans of the complex process say the Commission’s timeline is extremely ambitious. Negotiations over the budget are always long and tough — and things are likely to be even tougher this time around as the U.K.'s departure leaves a hole of roughly €12 billion to €13 billion per year.

The current seven-year budget amounted to some €1 trillion, and if the Commission gets its way, the next one will be at least as big despite Britain leaving. Countries, regional governments and lobby groups across the Continent will be trying to influence the budget process as it plays out, aiming to grab as much of the pie as possible.

The European Parliament will also be heavily involved as it has to give its consent for the budget to pass. And the budget is approved only when the EU's member countries sign off unanimously in the European Council.

Here's a graphic guide to some of the key issues in the budget battle:

This article is part of POLITICO’s new coverage of the EU budget, tracking the development of the seven-year Multiannual Financial Framework, and the first EU budget that will face a low or no contribution from the United Kingdom. This coverage includes the Budget Briefing newsletter every Monday afternoon. Email pro@politico.eu to request a complimentary trial.