Why was the offer of dominion status by Lord Irwin rejected by Indian National Congress?

In an effort to win them over, the Viceroy, Lord Irwin, announced in October 1929, a vague offer of ‘dominion status’ for India in an unspecified future and a round table conference to discuss a future constitution. This did not satisfy the Congress leaders. The radicals within the Congress, led by Jawaharlal Nehru and Subhas Chandra Bose, became more assertive. The liberals and moderates, who were proposing a constitutional system within the framework of British dominion, gradually lost their influence.