Now, for the hard part: keeping all varieties of Democrat on the same team

The counting is over and even Wall Street has joined the celebration of Democrats taking back control of the Senate in the United States. But there are still plenty of pitfalls ahead for the Democrats even with the numbers in both houses of Congress.

Major reform on everything from climate change to gun control or taxes is a lot closer this morning but still faces hurdles not just from the rabid Republicans still there but also from the moderate Democrats whose vote cannot always be counted upon.

The amazing race in Georgia is obviously an enormous political boost to the Biden agenda with him now having the deciding vote in the Senate as well as a small majority in the House of Representatives.

As Australians well know from recent years of hung parliaments and thin majorities, every vote is crucial and keeping your own side in line can be just as fraught as negotiating across the aisle.

In the Senate in particular there is little room for error with a 50-50 tie to be broken by a very busy vice-president Kamala Harris who will have to be on constant call in Washington DC when Congress is sitting.

It is not the first time the situation has occurred; the last time being under George W Bush 20 years ago where the balancing act often hampered major reform, such as changes to immigration law.

And who can forget what compromises the last Democratic president had to make on his ambitious health bill despite having the majority in both houses.

While just hearing the words “Minority Leader Mitch McConnell” is a victory for the Democratic lawmakers, the US political scene is now so poisoned and polarised it will challenge incoming majority leader Chuck Schumer and even the renowned bipartisan political skills of long time senator Joe Biden.

Until now the focus has been on the radical left side of the Democratic Party, from Bernie Sanders to the so-called “squad” of progressives in the House who have already listed their demands from a Biden administration.

Attention will now shift to the moderate and so-called “blue dog” senators who will be just as crucial pulling the other way.

First is West Virginia Senator Joe Manchin who is so independent he often voted for Trump initiatives and is on the opposite side to the squad on issues like defunding the police. His vote will be crucial and he will be a counter to any hopes/fears of a Biden presidency moving too far to the left.

Then there is Senator Kyrsten Sinema who was the first blue crack in the red Arizona wall even before the last presidential election. Although she was the first openly bisexual Senator she won by making herself a “conservative” Democrat who has appealed to Republicans and often voted with them in Congress.

While these are the two most obvious dissenters for Biden, a tied Senate means every ambitious senator with their own agenda and grievances will think they will be able to threaten or blackmail their now critical vote.

And the threat of defections is even more crucial now. Democrats have not forgotten the betrayal of former vice presidential candidate Joe Lieberman, who switched to become an independent in 2006 — though the last change of party was Republican Arlen Specter, who actually became a Democrat in 2009.

It should also be noted that the Republicans have their share of independent thinkers who could be swayed to vote with the Democrats and they include Susan Collins, Lisa Murkowski and Mitt Romney — although with his nemesis Trump now gone he might swing back to the right.

Before the horse-trading begins, Biden can take comfort that at least a Democratic-controlled Senate will mean that his own cabinet choices should now be confirmed. The fact he has already picked a team that could pass a hostile Senate might show the careful way forward for him despite the Georgia win.

It might also explain why Wall Street did the opposite to what was expected and rose overnight not just on hopes of an infrastructure cash splash but also recognition things just might not be as bad as they feared.