The Topeka Constitutional Convention met in opposition to the first territorial legislature, from which free-staters had been excluded, and that they called "bogus".
The constitution was sent to Congress and approved by the House on July 2, 1856, but, opposed by President Pierce, failed in the Senate by two (Southern) votes.
It was approved in a rigged election in December 1857, but it was overwhelmingly defeated in a second vote in January 1858 by a majority of voters in the Kansas Territory.
[1] In the 1856 election the free-staters achieved a majority in the legislature, and they called for another constitutional convention, to head off approval of the Lecompton Constitutution.
In April 1860, the United States House of Representatives voted to admit Kansas under the Wyandotte Constitution.