Mayawati walked out of the Upper House before formally announcinh her resignation, ANI reported.
"Let me speak or I will resign," Mayawati had said.
RJD president Lalu Prasad came out in support of the BSP leader, and offered to send her to the upper house from Bihar. Mayawati's current term would have ended in April next year and her party, with just 18 MLAs in the Uttar Pradesh Assembly, is not in a position to send her to Rajya Sabha.
"Today would be remembered as a black day in the history when a highly respected Dalit leader was not allowed to raise the voice of poor in the Rajya Sabha," Lalu said reacting to Mayawati's resignation.
"If Mayawati wishes, we will send her to Rajya Sabha from Bihar," the RJD president whose party has 80 MLAs in 243-member Bihar Legislative Assembly said. "We are with her."
In her speech, Mayawati lashed out at the NDA government for not doing enough to stop the atrocities on Dalits.
"Since the time the BJP has come to power, there has been exploitation of the Dalits, poor, minority, and backward castes," she said.
She was speaking on the issue of Saharanpur violence.
"The Dalits were suppressed in Saharanpur but the government did not do anything about it," she said.
"No community is safe in UP, but the condition of the Dalits is worse," she added.
After she stormed out of the House, the opposition disrupted the proceedings which led to adjournment.
Mayawati, in her speech, hit out at the government for not doing enough to stop atrocities against the Dalits||RJD chief Lalu Prasad has offered his support and offered to send the BSP chief to the Upper House from Bihar