On 4th January 1649 the remaining MPs, known as the Rump reassembled.
Many feared the army. This was clearly demonstrated in the first two years of the Commonwealths existence. The army fulfilled its role by suppressing threats from the Levellers, in particular the Leveller soldiers at Burford in May 1649 that led to multiple leaders being shot.
In 1649, 125 Acts of parliament were passed, reducing to just 51 in 1652.
High taxation - maintenance of the army, which they could not reduce or dispense.
Wars in Ireland, Scotland, and the dutch led to a shortfall in revenue of £700,000 in 1653.
Cromwell became Lord Protector on December 16th 1653
Cromwell was appointed commander-in-chief and in september 1650 defeated the Scots at Dunbar. The First Anglo-Dutch War took a toll on the treasury, so the monthly assessment was raised to £90000.
Cromwell ordered the dissolution of the Rump after he found out that they were planning to rush through a bill for elections before addressing any of the reforms desired by the army.