"We will work together with the BJP if it decides to contest the next general elections under the Gujarat Chief Minister's leadership and wrest power from the UPA," he said.
"Coming from the Extremely Backward Caste background that he does, Modi is the right choice for the prime minister's post given his credentials as an administrator," Kushwaha told reporters here during his party's conclave.
On Bihar Chief Minister Nitish Kumar's antipathy towards Modi, the RSLP president said he "harbours ill will towards any EBC leader who dreams big".
This is the first time that Kushwaha, an ex-Rajya Sabha MP and known Nitish-baiter, announced that he would back Modi's prime ministerial candidature.
The RLSP's support to Modi came a day after Bihar BJP adopted a resolution urging the party's central leadership to declare Modi as its prime ministerial candidate without delay.