The European Central Bank is all but certain to keep policy on hold today, taking its time to evaluate whether its most recent stimulus is enough to arrest a rapid decline in sentiment. 

With economic powerhouse Germany skirting a recession, the ECB has already been forced to backtrack on plans to tighten policy and now faces calls to do more.

This is despite the root cause of the downturn, weak demand from abroad, is largely beyond its policy reach. 

In the latest move in his global trade war, US President Donald Trump yesterday threatened to impose tariffs on $11 billion worth of European Union products, while the International Monetary Fund cut its forecast for world economic growth this year. 

Meeting earlier than usual so they can attend the IMF's spring meeting in Washington this week, ECB policymakers are likely to discuss market speculation about further delays to their first post-crisis rate hike and the side effets of years of negative rates.

But they are likely to stick to a long-standing line that ultra-easy policy is working as intended, and that banks remain net benefactors of record low rates so there is no acute need to compensate them for the hefty fee they pay to park their excess cash at the ECB.

The latter debate, simmering since 2016, is likely to intensify today, however, as the growth slowdown suggests the ECB's -0.4% deposit rate could stay in negative territory even longer than now expected. 

ECB President Mario Draghi has already said the euro zone's central bank must consider whether it needs to mitigate the side-effects of negative rates. 

One option under study is a tiered deposit rate, which would shield lenders from part of the cost, in a similar vein to moves by central banks in Switzerland and Japan.

The ECB announces its rate decision at 12.45pm, followed by Draghi's news conference later. The Federal Reserve will publish the minutes of its latest policy meeting later this evening. 

But personnel changes at the ECB risk delaying the discussion about tiering or whether to push out a rate hike even further. 

With ECB chief economist Peter Praet leaving in May and Draghi in October, policymakers are reluctant to decide on a fundamental revamp of monetary policy before new leaders take charge of the 19-country euro zone's most powerful institution. 

Outgoing ECB chief economist Peter Praet

Central Bank Governor Philip Lane is replacing Mr Praet. 

Draghi's successor will not even be named until after the European elections in late May, with confirmation likely only in late summer. 

A survey of lending published this week also eased the urgency for any mitigating measures as lenders said they expected business credit to grow and lending standards to ease this quarter. 

The ECB also needs to keep its remaining policy powder dry in case of market turbulence around Brexit and the continued escalation of a global trade war, with risks growing that the US administration will turn its attention to Europe. 

Another complication with shifting to a tiered deposit rate is that it would signal low rates for longer, which is inconsistent with the bank's guidance for a growth rebound later this year and a rate hike in 2020.