Why did the women's suffrage movement aim at a constitutional amendment?

The women's suffrage movement aimed at constitutional amendments because the supreme court ruled against efforts to apply the 14th amendment to women. Also, they wanted right to vote in all elections. Women suffrage movement was the struggle for the right of women to run for office to vote and above all women's rights movement. The self-governing British colony of New Zealand was the first country to grant national level voting rights to their women. South Australia in 1898 granted full suffrage giving women right to stand for parliament and right to vote.