The last day of November was billed as a key date for fixing HealthCare.gov, but the real test may come on Dec. 9, when Senate Democrats return to Washington from a two-week break.

Improvements to the error-riddled federal portal, which is used by prospective health care buyers in states that didn’t set up their own exchanges, are readily apparent but won’t be enough to keep some Democratic senators from pushing to delay enforcement or extend deadlines for parts of the law.

Sen. Jeanne Shaheen, D-N.H., has led an effort to extend the window for open enrollment in the exchanges at least two months further into 2014.

“We lost two months of valuable time because of problems with healthcare.gov. We should give people more time to sign up for insurance by a minimum of two months,” Shaheen said in a statement Wednesday.

Likewise, an aide noted that concerns raised by Sen. Joe Manchin III, D-W.Va., about enforcement of the individual mandate penalty that applies to individuals who opt against buying health insurance were not part-and-parcel of the issues with the website. Manchin has introduced legislation along with Illinois Republican Sen. Mark S. Kirk that would delay mandate penalties for a year.

That would be in line with what Sen. Mary L. Landrieu, D-La., has said previously about her proposal that would require insurance companies to grandfather certain health plans that are offered in 2013.

But Shaheen, Landrieu and Manchin appear to be in the minority among Democrats, who have been trying to rally around the law in recent days. And their leaders don’t appear to be readying the floor for any action on Obamacare legislation.

Majority Leader Harry Reid, D-Nev., demurred when asked Tuesday by KSNV-TV in Las Vegas if he supported the legislation floated by Landrieu and Shaheen.

“We’re going to have to wait and see,” Reid said.

“Politics is ebbs and flows, and this has been not fun the last month or so, but it’s getting better even the last few days,” Reid said during the interview, in which he also said the health care overhaul would prove a boon to Democrats seeking re-election in 2014, such as Landrieu and Shaheen. It’s a position that runs counter to quite a bit of conventional wisdom.

The White House’s new push this week to encourage enrollment in the Obamacare insurance exchanges drew the predictable criticism from the GOP, including a new call from the top Senate Republican to scrap the law all together.

Still, the White House and Democrats in both chambers are beginning a renewed campaign to defend the law, with President Barack Obama holding events aimed at encouraging supporters to help promote the benefits of signing up during the open-enrollment window.

On Wednesday afternoon, Obama spoke to younger supporters at the White House Youth Summit in a bid to boost enrollment among the group sometimes known as “young invincibles.” Younger people getting insurance through the exchanges helps diversify the risk pool, which should help to keep premiums down in future years.

“I’m going to need you all to spread the word about how the Affordable Care Act really works, what its benefits are, what its protections are and most importantly, how people can sign up,” Obama said. “For your friends and your family, the most important source of information is not going to be me. … It’s going to be you.”

Obama was encouraging the sometimes raucous crowd to use social media, from Facebook to Twitter to Instagram, to support the law, but he also suggested they go further.

“If you’re a student body president, set up a conference on campus. If you work at a nonprofit, open your doors and use your email list to help people learn the facts. If you’ve got a radio show, spread the word on air. If you’re a bartender, have a happy hour — and also probably get health insurance because a lot of bartenders don’t have it.”

Likewise, Senate Democrats have joined their House counterparts in setting up an Obamacare “strike team.”

A Democratic aide confirmed the new messaging effort features a group of Democratic caucus members including Reid, Majority Whip Richard J. Durbin of Illinois and Conference Vice Chairman Charles E. Schumer of New York, as BuzzFeed reported Tuesday.

One of those Senate strike team members, Barbara Boxer of California, joined several House Democrats on a conference call Wednesday afternoon to make the case.

“We’re headed toward half a million people beginning the enrollment process. So, we’ve had a very good experience with our … computer situation,” Boxer said of California’s state-run health insurance marketplace. “What I predict is the same thing’s going to happen across the country. Some states are working more smoothly than others, others are catching up, and the national exchange is catching up.”

Boxer has successfully enrolled in D.C. Health Link. The District of Columbia’s exchange is the one members and staff must use to maintain federal employer contributions to their health care as they transition out of the Federal Employee Health Benefits system.

“The product is terrific, OK? I went on the exchange; I found a great product,” Boxer said. “Before the website was fixed, it’s like you drove past a store and saw a beautiful product in the window that you wanted, but the door was locked, and you wouldn’t get in. Now you can get in.”