Updated at 4:41 p.m. on Nov. 16.

In advance of the Senate's health care talks, expected to begin next week, NationalJournal.com will explore the big issues the Senate will debate, their possible solutions and the key votes on each one. Today: immigration.

Early in the reform debate, immigration looked like it would be the most contentious issue. After all, it was President Obama's remark that reform wouldn't give insurance to illegal immigrants that prompted Rep. Joe Wilson, R-S.C., to shout, "You lie!" It became a big issue in the House, especially after members of the Congressional Hispanic Caucus threatened to withhold support unless Democrats maintained language allowing illegal immigrants to purchase private insurance through the exchange but barring any federal payments or subsidies on their behalf.

While the Senate has a much smaller Hispanic presence (only New Jersey Democrat Bob Menendez), the immigration issue still looms and could be a deciding factor in a final vote. While none of the bills would have illegal immigrants getting government coverage through Medicare or Medicaid or being eligible for federal subsidies, debate still remains on their involvement in the health insurance exchange. Here's a look at the Senate's options on abortions and what key votes they could bring.

Exclude illegal immigrants and legal immigrants in the country for less than five years from the health insurance exchange

Thirteen years ago, in an effort to stop immigrants from seeking America as a source of cheap health care, Congress imposed a five-year waiting period for immigrants trying to get benefits from Medicare or Medicaid. The most restrictive current proposal would apply this five-year ban to immigrants trying to purchase private insurance from the health insurance exchange. It would also ban all illegal immigrants from getting insurance through the exchange. Though this far-reaching proposal isn't in any of the current bills, similar language was proposed by Sens. Charles Grassley, R-Iowa, Jon Kyl, R-Ariz., and John Ensign, R-Nev., and is sure to attract some Republican votes.

Exclude illegal immigrants from the health insurance exchange, but allow all legal immigrants

This plan is similar to the one passed by the Finance Committee, which excluded illegal immigrants from the health insurance exchange. It's also expected to be the one Majority Leader Harry Reid, D-Nev., goes with, even though it is different from the language in the House bill. In passing the Finance Committee, it got the support of swing voters like Olympia Snowe, R-Maine, Bill Nelson, D-Fla., Blanche Lincoln, D-Ark., and Kent Conrad, D-N.D., though they haven't staked out firm positions on the latest immigration proposals.

However, this proposal brings up more questions, including whether to count illegal immigrants as part of families seeking subsidies or how much identification is required to purchase an exchange plan. Menendez has been fighting to allow illegal immigrants to count in "mixed status" families that include both legal and illegal immigrants to ensure that families don't get short-changed on subsidies and meeting poverty level requirements. Meanwhile, several Republicans in both the House and Senate are lobbying for immigrants to be required to show two forms of state-issued identification to better prevent fraud. Current legislation only requires simple identification, and Democrats say that previous enforcement measures beyond that have caught few illegal immigrants relative to their cost.

Allow illegal and legal immigrants in the health insurance exchange

The last-ditch appeal from the Hispanic Caucus put this language in the House bill, which is similar to the one passed by the Senate Health, Education, Labor and Pensions Committee. That language passed with the support of Jeff Bingaman, D-N.M., who later told the New York Times that Democrats were not trying to expand health care to illegal immigrants. With the Senate's small Hispanic presence and desire to reach moderates, it is unlikely that the final bill would extend the health insurance exchange to illegal immigrants.

Read about other divisive issues in the Senate: the public option and abortion.

CORRECTION: The original version of this report incorrectly stated eligibility information was changed in the House bill. The original language allowed illegal immigrants to use their own money to purchase private insurance.

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