Republicans argue it's necessary to repeal Obamacare before replacing it because this is the best chance to repeal Obamacare. If Republicans miss this window of opportunity, it may be years until Obamacare is repealed.

Reconciliation is a powerful—but tricky—tool to use, as it allows Senate majorities to overcome the filibuster and pass major legislation with only 51 votes in the Senate (as opposed to the usual 60). In 2010, Democrats used it to pass parts of Obamacare over Republican objections. Now, Senate Republicans want to use it for repeal.
What makes reconciliation so tricky, however, are the very specific rules that govern its use. According to these rules, reconciliation bills must only contain subject matter that has a direct budgetary impact. Otherwise the reconciliation bill “loses privilege,” or loses the ability to avoid the filibuster.
That means that under a simultaneous repeal-and-replace effort, 60 votes would be required to repeal Obamacare, instead of 51—an impossibility, as Republicans only have 52 votes in the Senate.

Republicans think Americans have given their party a mandate to repeal Obamacare. They see the system as fundamentally flawed. The only way to fix it is to tear it down and start from scratch.

Obamacare is crumbling, and the health insurance market in America needs significant reform. Republicans have put forward a myriad of proposals to do so. However, responsible lawmaking requires this process to be done in the light of day, with participation by all members of Congress, and with buy-in from the American people.Republicans received a mandate from voters to repeal Obamacare, and to fix the country’s health care system. Fulfilling this promise requires lawmakers to treat the repeal effort with the utmost care. That means using the reconciliation process for repeal only, and then moving forward with the open debate and deliberation that such critical policy decisions deserve.

Should Obamacare be preserved? | The Tylt