A chance of a brace of interest rate cuts next week and on Melbourne Cup Day from the Reserve Bank that would take the official cash rate to 0.5 per cent is growing amid concerns the move to impeach Donald Trump could make global economic conditions even worse.

After RBA governor Philip Lowe used a speech on the state of the global economy to warn Australia could not hold out if central banks across the world reduced their interest rates, economists said looser domestic monetary policy was almost certain.

The impeachment process against US President Donald Trump has added to global economic problems and may force the Reserve Bank into back-to-back interest rate cuts. Credit:Alex Ellinghausen

Dr Lowe made the speech before the move by Democrats in the United States to start impeachment proceedings against Mr Trump over his dealings with Ukraine.

Financial markets put the chance of a rate cut on October 1 at almost 80 per cent with the same markets pricing in a 0.5 per cent cash rate by early next year.