"The time for rhetoric and ceremonial votes in Congress is over," Palin wrote in the email. "The time to take serious action to stop Obamacare is now. Join us in urging Senators - Don't Fund Obamacare! Just remember - if you fund it, you own it!"

Palin remains popular among grassroots conservatives and her support could fuel additional Tea Party backing for the defund ObamaCare position.

Sens. Ted Cruz (R-Texas), Mike Lee (R-Utah) and Marco Rubio (R-Fla.) are among the conservatives who argue the GOP should risk a government shutdown over defunding ObamaCare.

But other Republicans are sounding the alarm bells about the strategy, arguing the GOP will be blamed for a shutdown.

Some even argue forcing a shutdown would be the only way Republicans could lose their House majority next year.

Speaker John Boehner (R-Ohio) is calling for his party to back a short-term government funding bill set at the levels of the sequester, which imposed automatic spending cuts on the government. He is not advocating that the bill strip all funds for ObamaCare.