The Senate seems to be debating Obamacare repeal, a highway bill, reviving the expired Export-Import Bank, something about Iran and Israel, and cutting off subsidies to abortion-industry leader Planned Parenthood — all at the same time. What's going on here?

Here's the story, boiled down to its essential elements:

1. The bill in question is the highway bill

The federal Highway Trust Fund runs out of money Friday. President Obama, the road-building industry and much of the business world want a 6-year extension, but nobody can agree about how to fund it (whose taxes to hike). So the House has passed a four-month extension of funding for the highway bill, pushing a fight over revenues until after the August recess.

The Senate has taken up a six-year highway bill. The current bill is the fruit of a deal cut between Environment and Public Works Committee Chairman Sen. Jim Inhofe, R-Okla., and the committee's top Democrat, Sen. Barbara Boxer of California. Majority Leader Mitch McConnell really wants to pass this bill.

2. Obama, Senate Democrats and some Boeing-state Republicans want Ex-Im Bank to be revived in the bill

The Export-Import Bank is a federal agency that used to subsidize U.S. manufacturers by extending taxpayer-backed financing to foreign companies buying U.S. goods — mostly Boeing jets. The agency's charter expired June 30, and it is now in liquidation.

The White House, K Street, almost all congressional Democrats and some congressional Republicans want to bring Ex-Im back to life. The White House demanded an Ex-Im renewal provision be stuck into the unrelated highway bill, threatening to veto the bill if it didn't have Ex-Im in it. Senate Democrats have done the same.

So McConnell, who opposes Ex-Im, cleared a path for Ex-Im to stuck into the bill through an amendment. That amendment cleared a 60-vote procedural hurdle Sunday, meaning it will likely be inserted into the bill.

3. Conservatives wanted their own unrelated amendments

If Boeing-state senators such as Maria Cantwell, Lindsey Graham, and Mark Kirk get to add their own non-germane amendments, shouldn't conservatives get votes on their pet policy preferences.

Conservatives Ted Cruz, Mike Lee and Rand Paul had queued up two amendments that would either pass, or force Democrats to take uncomfortable votes. One was an amendment by Paul and Lee to cut off federal subsidies to Planned Parenthood, the abortion provider that has recently been revealed to be a major baby-parts supplier to the biotech industry. Another amendment was an effort by Cruz to prohibit Obama's Iran nuclear deal until Iran recognizes Israel and releases all U.S. hostages.

Either amendment might pass or would at least make many Democrats voting "No" look very bad.

4. McConnell effectively barred all other amendments, except one to repeal Obamacare

McConnell, presumably to prevent the Highway bill get getting bogged down with veto bait for Obama, resorted to an old Harry Reid tactic: he "filled the tree," basically blocking all amendments to the highway bill, but two: the Ex-Im revival, and an amendment to repeal Obamacare.

The Obamacare amendment, of course, failed on Sunday to get 60 votes. Nobody ever thought it could pass.

5. Republicans could, if they wanted, get another vote on Obamacare, which could pass

Lee pointed out Friday that Republicans could use parliamentary gymnastics to get another vote on Obamacare repeal, and that this could allow them to attach the Obamacare repeal provision to the Highway bill with only 51 votes.

Other parliamentary fun might happen Monday night or Tuesday, and my colleague Susan Ferrechio lays that out in this story, so stay tuned.