There's only one game in town this week and it's yet another down-to-the-wire standoff between the Republican-controlled House, the Democratic-controlled Senate and President Obama as they try to reach agreement on a short-term spending plan before the government shuts down next Tuesday morning.

Senate Majority Leader Harry M. Reid (D-Nev.), House Speaker John A. Boehner (R-Ohio), and Senate Minority Leader Mitch McConnell (R-Ky.). (Joshua Roberts/Bloomberg)

The House started the process last week by passing a measure that would extend government operations through mid-December in part by repealing the Affordable Care Act. The House bill is expected to be changed considerably in the Democratic-controlled Senate and then sent back to the House with just days, if only a few hours, until the start of the new fiscal year.

So who will be the main players as this next round of fighting over spending begins with a shutdown looming? Here's a look at some key characters:

Senate Majority Leader Harry M. Reid (D-Nev.): The Nevada Democrat calls the House's proposed continuing resolution "dead" and he plans to strip it bare of provisions that would repeal the health-care law, known as Obamacare. As majority leader, Reid keeps the trains running and knows the Senate playbook better than most. He may need to use several parliamentary gimmicks to ward off threatened filibusters and other delays by a small band of Senate Republicans. Reid is expected to call up the House bill on Monday afternoon, with the first key test vote coming Wednesday.

Senate Minority Leader Mitch McConnell (R-Ky.): Will McConnell be a leader or an independent political operator? We'll be asking this question every time the Senate faces a key vote between now and when McConnell faces reelection next November.

The Senate Republican Conference is bitterly divided over how to proceed, with Sens. Bob Corker (R-Tenn.), Jeff Flake (R-Ariz.) and Johnny Isakson (R-Ga.) among those believing that attempts to repeal Obamacare as part of a short-term spending bill could cost the party any chance of retaking the Senate next year. But McConnell faces more political pressure from conservatives (see below), who are eager for a fight over the health-care law in the upper chamber. At least some of McConnell's GOP colleagues will be unhappy no matter how he comports himself.

Sens. Ted Cruz (R-Tex.) and Mike Lee (R-Utah): These two conservatives are poised to pick up the fight mounted by House Republicans and push to repeal the health-care law in the Senate. But under Senate rules, Reid needs only 51 votes to defeat any amendment they might propose to eliminate the health-care law. With 54 members of the Senate Democratic caucus, Reid will easily hold off Cruz and Lee.

So what will Cruz, Lee and others do? They can filibuster the House-passed bill, even though that means blocking the very Obamacare-defunding measure that he wants Congress to approve. That's why Cruz and Lee appeared to relent a bit last week when they acknowledged that they're unlikely to succeed in the Senate.

Lee assured Sunday that their effort won't lead to a government shutdown: "We all know that the government is going to be funded. The question is whether it will be funded with Obamacare or without," he told NBC's "Meet the Press."

Knowing that there's no chance of repealing Obamacare in the Senate, which other Senate Republicans plan to join Cruz and Lee in their fight? Will possible presidential contenders Sens. Rand Paul (R-Ky.) and Marco Rubio (R-Fla.)? Anyone else?

The House Republican leadership: Speaker John A. Boehner (R-Ohio), Majority Leader Eric I. Cantor (R-Va.), Majority Whip Kevin McCarthy (R-Calif.) and their lieutenants are struggling to figure out what to do once the Senate sends back a budget bill. Reid is expected to wait until the last minute to seek final passage -- possibly next weekend -- leaving GOP leaders very little time to rally their conference and determine how to proceed.

Will they decide to strip out anything related to repealing Obamacare and pass a "clean CR" with Democratic support, or will they keep the defunding language in the bill, pass it again and send it back to the Senate? Much of what leadership decides to do will depend on the next two groups of lawmakers.

Reps. Steve Scalise (R-La.), Tom Graves (R-Ga.) and Jim Jordan (R-Ohio): This trio represent the hundreds of members of the Republican Study Committee, the conservative caucus that includes most of the House GOP Conference and aggressively pushed Boehner to include language defunding the health-care law in the continuing resolution. Scalise currently chairs the RSC, Graves first drafted the language that would repeal Obamacare while keeping the government funded and Jordan is a former RSC chairman who remains active with the group and keeps channels of communication open with leadership.

Considering the RSC's numbers, this is the group of House Republicans that Boehner will need to worry about the most. Several group members voted en masse against Boehner for speaker earlier this year and many likely would renew calls to unseat him if he goes against their wishes.

Rep. Adam Kinzinger (R-Ill.) (AP)

Reps. Adam Kinzinger (R-Ill.), Devin Nunes (R-Calif.) and Jim Renacci (R-Ohio): This trio represents more average, rank-and-file Republicans who believe in conservative principles but aren't necessarily members of the RSC. (Of this group, only Renacci is an RSC member.)

If Boehner decides to strip out language defunding Obamacare, he'll need to rely on these folks to vote with him and House Democrats to approve a short-term spending plan.

House Minority Leader Nancy Pelosi (D-Calif.) and House Democrats: After last week's vote on the continuing resolution in the House, Pelosi wrote to her Democratic colleagues instructing them to "keep their power dry" as they await the next steps. "Our continued unity will only strengthen our leverage in this fight and the upcoming debt ceiling debate as well," she said.

Pelosi suggested Sunday that she'd like to once again be House speaker and she knows that Boehner may once again need her and Democrats to help him quickly pass legislation that most Republicans don't like. Before she agrees to do so, she may force the speaker to give Democrats something they want. What that is remains to be seen.

Paul Kane contributed to this report.