US House Speaker John Boehner became a casualty of the battle over funding for the women's health organisation Planned Parenthood as he appeared to have capitulated to Republican Party conservatives over the issue by resigning from Congress on Friday.

The GOP conservatives had reportedly been moving against Boehner in recent weeks pressing him to take more forceful action on defunding Planned Parenthood even at the cost of risking a government shutdown.

The Speaker eventually decided to step down "for the good of the Republican Conference and the institution," aides said, according to the Guardian.

On Sunday, Boehner vowed that Congress will avoid a government shutdown this week, according to a Reuters report.

Speaking on CBS' Face the Nation two days after his surprise resignation, Boehner assured that the House would pass a government funding bill this week, which does not meet conservatives' demands to cut off money for Planned Parenthood.

Boehner's resignation sent shock waves to the GOP caucus and sparked a race in the battle for House speakership ahead of the upcoming reshuffle in party ranks, CNN reported.

Boehner, a 13-term Ohio Republican, reportedly told party members in a closed-door session that he will step down at the end of October.

He also endorsed House Majority Leader Kevin McCarthy for the House speakership. "I am not going to be here to vote on the next Speaker. But that's up to the next members. But having said that, I think that Kevin McCarthy would make an excellent Speaker.''

Following Boehner's pronouncement, one lawmaker was reportedly "stunned'' and said there was "some anger'' in the room "against the people who caused this to happen,'' Fox News said.

On Saturday, Rep. Peter Roskam, R-Illinois, called for a special conference meeting for the next Speaker.

Rep. Steve Scalise, R-Louisiana, meanwhile, said Boehner's decision to resign was "one of the most selfless things I've ever seen."

"Healing our divisions and uniting behind the conservative policy solutions the American people deserve will help our members and it will empower the new leaders we select," he said in a letter to colleagues.

Boehner's exit was reportedly prompted by a planned revolt from conservative colleagues who want to take a more ideological purist stance not only on the Planned Parenthood controversy but on other divisive issues like Obamacare and the Export-Import Bank.

More recently, the issue of funding for Planned Parenthood has raised the alarm about another possible government shutdown. Conservative Republicans have sought to tie provisions to defund the organisation to a government funding bill, amid outrage over videos that allegedly show officials from the group discussing the sale of foetal tissues, CNN said.

The endorsement of McCarthy appeared to have sparked confusion among GOP members as some think that "it would mark the continuation of an incredible ascent for the California Republican'' if he wins the gavel.

Pressed to react on Boehner's resignation, President Barack Obama said in a press conference with Chinese President Xi Jin Ping Friday afternoon that Boehner was "a leader who understood that in governance, "you don't get 100 percent of what you want." He called on the next speaker to "not resort to shutting down the government when faced with significant differences in opinion.''