Just days before open enrollment begins for 2019, Obamacare is looking a lot healthier than it did at this time last year. Enrollees generally will have more choices and see lower rates on the exchanges.

Obamacare has proven resilient despite efforts by President Donald Trump and Republicans in Congress to undermine it after failing to repealthe landmark health reform law. Enrollment held up better than expected for 2018 -- nearly 11.8 million Americans signed up for coverage on the federal and state exchanges, down only 3.8% from a year earlier. A larger share of people who picked plans completed their enrollment by paying their first month's premium.

Yet, while Congress is no longer actively trying to roll back the law, the Trump administration has made many moves over the past 21 months that could have an impact on the program. The key questions are how the elimination of the individual mandate penalty and the introduction of alternative health care options, such as short-term plans, will affect enrollment for 2019.

Americans can start signing up on Thursday, with open enrollment running through Dec. 15 in most states. Some states that operate their own exchanges are extending enrollment as long as until January 31.

Here are four ways the Affordable Care Act is changing for 2019:

Premiums are lower: For the first time since the exchanges opened in 2014, the average rate for the benchmark silver plan will dip.

The monthly premium will slide to $405, down from $412 last year. (These prices are for policies sold to 27-year-olds shopping on the federal exchange, which handles enrollment for 39 states.)

The rate changes vary widely depending on the state. Some will see even bigger drops for the benchmark plan, upon which premium subsidies are based. In Tennessee, for instance, the rate will decline 26%, while Pennsylvania residents will find a 16% decrease.

On average, 2019 premiums are dropping a bit or staying flat in many parts of the country. However, they would be dropping even more if the mandate hadn't been repealed and access to more loosely regulated plans weren't expanding. — Cynthia Cox (@cynthiaccox) October 26, 2018

Other states, however, will see their rates rise. North Dakota leads the pack with a 21% jump.

States that run their own exchanges are also enjoying declines or more restrained premium increases. In Pennsylvania, rates will fall 2.3%, while in Colorado, they are inching up 5.6%.

While the Trump administration is taking credit for stabilizing the Affordable Care Act, industry experts say insurers are holding the line on rates largely because they raised them so much a year ago in response to the uncertainty emanating from Washington over the future of the repeal effort. The benchmark plan premium spiked 37% for 2018 and is up 85% since 2014. Many insurers are breaking even or have started making a profit in the individual market after several years of racking up hundreds of millions of dollars in losses.

Also, several states have also taken steps -- with the approval of the Trump administration -- to insulate insurers from high-cost enrollees. In Maryland, which recently instituted such a reinsurance program, rates for 2019 will now drop by 13%, instead of rising by 30%.

Still, premiums could have dropped even more across the board without changes made by the Trump administration, according to a Kaiser Family Foundation analysis. Congress' elimination of the penalty, Trump's ending of the cost-sharing subsidies and the administration's expansion of Obamacare alternatives are pushing up the benchmark silver plan's premium by 16%.

On average, 2019 premiums are dropping a bit or staying flat in many parts of the country. However, they would be dropping even more if the mandate hadn't been repealed and access to more loosely regulated plans weren't expanding. — Cynthia Cox (@cynthiaccox) October 26, 2018

Subsidies will be lower too: One benefit of the rate hike for 2018 plans was that federal premium assistance jumped too. The average monthly subsidy jumped to $558, up from $382 a year earlier.

That meant that many consumers could use the extra help to buy gold-level plans or to reduce the price of bronze policies to very little -- or in some cases, nothing. For instance, in Nashville, Tennessee, a 40-year-old could pick up the cheapest gold plan for $440 a month or the least expensive bronze one for $0 this year, according to Kaiser.

With premiums easing for 2019, subsidies are too -- assistance will drift down to $544 a month, on average. The same Tennessean will have to pay $533 for the cheapest 2019 gold plan and $62 a month for the least expensive bronze plan.

Consumers will have more options: Those shopping on the exchanges will find more insurers and choices of Obamacare plans for 2019.

Companies -- from titans like Anthem to start ups like Oscar and Bright Health -- are returning to the marketplaces because they see an opportunity to make money on the exchanges, experts said. This is a big change from the last two years, when red ink and political uncertainty spurred many carriers to jump ship.

Some 155 insurers will participate next year, up from 132 this year -- though that's still down from the 167 that offered policies in 2017.

Five states will have only a single insurer, but that's less than the eight states in that position this year. Some 20% of consumers will have only one carrier to choose from, down from the current 29%.

But enrollees will get less guidance: The administration once again cut the funding for Obamacare's navigator program, which helps consumers sign up for coverage. It awarded only $10 million to 39 organizations for the upcoming enrollment season. That's down from $37 million that was distributed to 90 groups last year and reflects a more than 80% drop in funding over two years. Several states, including Iowa and Montana, will have no navigators, while their presence in Texas, New Jersey and several other states will be limited.

Instead, Trump officials are pushing people to sites operated by insurers or web brokers, broadening the use of direct enrollment sites. Consumer advocates, however, worry that these channels may not provide consumers with all the Obamacare choices available to them. Plus, agents are allowed to market alternative policies, such as short-term health plans , that don't provide all of Obamacare's protections.

Trump officials are also holding the advertising budget steady at $10 million. That's down from the $100 million that was spent in the final enrollment period under the Obama administration. The Trump administration justified the budget cuts last year by saying it was basing advertising on effectiveness and performance.

States that run their own exchanges, however, will continue to pour money into marketing. Some are trying new strategies: Rhode Island is advertising on pizza boxes, while Massachusetts will hold events in night clubs to try to reach young, single men, according to Georgetown University's Health Policy Institute.