A major stumbling block to the abolition movement was the influence of the pro-slavery supporters in Parliament and the House of Lords. A large number of parliamentary constituencies, especially those with small electorates, were under the control of rich landowners who could use their influence to sway local voters. Wealthy slave owners, such as William Beckford, were able to buy their way into high office and control of Parliament.
The Act of Union with Ireland in 1800 strengthened the abolitionist lobby (when 100 Irish MPs, most in favour of abolition, entered the Commons) but any changes to legislation were still met with strong opposition.
During the early 19th century, the abolitionists came to see the need to campaign for the election of members sympathetic to the cause and eventually for political reform. In 1826, James Stephen issued 'An Address to the People and Electors of England', urging the election of Members of Parliament who would not be "tools of the West India interest". This helped paved the way for the second Abolition Bill.
In May, 1830, two thousand people met in London at Freemasons' Hall in support of abolition. James Stephen had died but his son George and his friends were there along with Clarkson and Wilberforce. George Stephen paid speakers to travel and "rouse the country". Their speeches stirred thousands. But Parliament still refused to act. It was now clear that Parliament itself had to be reformed before abolition could occur.
Electoral reform became a major campaign issue for many members of the abolition movement. When Henry Goulburn, a Tory politician and absentee slave-owner, stood as a candidate for Cambridge University in 1831, the Anti-Slavery Society campaigned against him. They circulated a broadsheet 'Address to the Electors of Cambridge University' claiming he had failed to improve conditions for the slave workers on his Jamaican estates, despite government reforms.
In 1832 'The Great Reform Act', supported by the Whigs, led by the Prime Minister Lord Grey, proposed wide-ranging changes to the electoral system. It met with significant opposition from the Tories, especially in the House of Lords where bills were twice rejected. The third bill passed but only after significant public pressure, the threat to flood the Lords with new Whig members and, finally, pressure from the King himself, fearful of revolution.
The Act granted seats in the House of Commons to large cities that had developed during the Industrial Revolution, and took away seats from those with very small populations. It also increased the number of individuals entitled to vote to one in five of the population.
The abolitionists campaigned to get those who supported abolition, elected. Lists were circulated telling voters if candidates were in support of abolition. Some candidates (as illustrated above) declared their support on posters. The December elections of 1832 swept half of those who had supported slavery out of Parliament, paving the way for the 1833 act.