WASHINGTON (Reuters) - U.S. Democrats on Sunday criticized the lack of women on a working group in the Republican-led Senate that will craft a plan to pass legislation to repeal and replace Obamacare. As the Senate begins to wrestle with a Republican healthcare bill narrowly approved by the House of Representatives last week, senators questioned why the 13-member working group put together by Senate Republican leader Mitch McConnell does not include any of the chamber’s five Republican women. “Women’s health is a big part of this and women are a majority of the population, and their health interests deserve to be contemplated in any reform,” Democratic Senator Dianne Feinstein of California said on NBC’s “Meet the Press.” Democratic Senator Patty Murray of Washington wrote on Twitter: “It matters to have women at the table — and it matters when they aren’t.” Republicans pushed their healthcare restructuring through the House on a 217-213 vote, handing President Donald Trump his first major legislative success. But the bill faces an uncertain future in the Senate, where Republicans have a narrow majority and several members have suggested they will develop their own plans. Democrats are united in opposition to the House bill. Trump pledged on Sunday that the effort to gut former President Barack Obama’s signature healthcare law would be successful. “Republican Senators will not let the American People down!,” he wrote on Twitter. “ObamaCare premiums and deductibles are way up-it was a lie and it is dead!” The Senate’s healthcare working group includes the Republican leadership, several committee chairmen and a combination of conservatives such as Ted Cruz of Texas and more moderate Republicans from politically important swing states such as Rob Portman of Ohio and Pat Toomey of Pennsylvania. Critics said the group’s lack of diversity would eliminate crucial viewpoints. “The GOP is crafting policy on an issue that directly impacts women without including a single woman in the process. It’s wrong,” Democratic Senator Kamala Harris of California wrote on Twitter on Saturday. Don Stewart, a senior aide to McConnell, said critics were getting “hung up on process” while ignoring the problems of Obamacare such as higher costs and limited choices. “So you can get caught up in process, or you can focus on the actual reality,” Stewart said in an email on Sunday. Republican Senator Susan Collins of Maine, who has been working on her own healthcare plan, said she was reaching out to moderate Democrats to try to find common ground. She did not criticize the working group’s all-male make-up but said she wanted to see a broader effort to replace Obama’s 2010 healthcare law. “I would like to see us put together a bipartisan group to solve this problem, of Democrats who acknowledge there are problems with the current law, that it is not working well in several states, and Republicans who also want to make sure that we’re not reducing coverage and we’re giving flexibility,” Collins said on ABC’s “This Week.” Senators have questioned aspects of the House bill, which would slash funding for Medicaid, the program that provides insurance for the poor, and roll back much of its expansion during the Obama administration. It also would allow states to opt out of some existing protections for people with pre-existing health conditions. While insurers could not deny insurance because of such conditions, they would be allowed to decide how much to charge. Senator Joe Manchin of West Virginia, one of the most moderate Democrats in the Senate, said his state “gets absolutely slammed” in the House bill because it has a lot of elderly residents and people with pre-existing conditions. “I just want to work and sit down and try to get something done, but no one’s asked us,” he said on CBS’s “Face the Nation” program. “Our congressional delegation says, ‘don’t worry, the Senate will fix it.’ And no one has asked any Democrat. And I am the most centrist.” White House Chief of Staff Reince Priebus said the White House would not dictate the process. “I think we want to let them do their work, let them work this out. They are all very mature. They all know what is going on. They all know the commitments we have made to the American people to repeal and replace a failing program in Obamacare,” he said on the “Fox News Sunday” program. 