“We did not need Mike,” President Donald Trump bragged to reporters after the Senate passed its tax bill with 51 of the 52 Republican senators in early December without Vice President Mike Pence’s vote.

It’s an unusual subject for a president to boast about. The vice president’s role as the president of the Senate is usually as a figurehead, not an active legislator. Joe Biden didn’t cast a single vote on the Senate floor during his eight years in office. Dick Cheney cast eight in his two terms, and Al Gore, during his two terms, cast four.

In just his first year, Pence has already cast six tie-breaking votes — on track to break a record that has stood since the 19th century: No vice president since 1861 has cast more than 10 tie-breaking votes during his term.

So it was almost surprising that the final vote on the tax bill passed without Pence’s tie-breaking support. Earlier in the year, when Senate Republicans passed their initial version of the bill, they needed Pence to break a stalemate over an amendment from Sen. Ted Cruz (R-TX).

It all comes down to the defining legislative dynamic of 2017: Republicans might control the White House, House, and Senate, but their slim majority and determination to pursue a partisan agenda have left them with a razor-thin margin of error. Pence’s role as president of the Senate — once seen as a last resort if negotiations failed — has become a cornerstone of the GOP’s legislative strategy.

It’s an unusual way for a vice president to wield his influence. But in Trump’s first year in office, Pence played an essential role in getting the Republican agenda over the finish line.

Mike Pence is on track to break a modern record

In only his third week in office, Pence was called to the Senate to break a tie.

Betsy DeVos’s nomination as education secretary had run into trouble in the Senate. No Democrats would vote to confirm her, and she lost the support of Sens. Lisa Murkowski (R-AK) and Susan Collins (R-ME), leaving the final vote count at 50-50. In need of a simple majority, Pence cast the tie-breaking vote, the first time a vice president’s vote was needed to confirm a Cabinet nomination.

It was the first of a series of consequential votes Pence took this year:

In July, he voted break an tie and start debate on the Republican Obamacare repeal effort.

In March, Pence voted in favor of overturning an Obama-era rule protecting state funding for Planned Parenthood. His vote was also needed to begin debate to overturn the rule.

In October, Pence broke the tie on a vote to overturn another Obama-era Consumer Financial Protection Bureau rule that bans banks and credit card companies from protecting themselves from class-action lawsuits in their customer contracts.

Pence broke the tie on a vote to overturn another Obama-era Consumer Financial Protection Bureau rule that bans banks and credit card companies from protecting themselves from class-action lawsuits in their customer contracts. In December, he voted in favor of Cruz’s amendment to the Senate’s tax bill that would extend tax-advantaged college savings accounts to elementary and secondary school, including home-schooling.

When Pence was picked to be Trump’s running mate, his role in a Trump administration wasn’t envisioned as a legislative tie-breaker. He has been seen as Trump’s Christian conservative moral compass — there to assure the evangelical base that the Trump agenda would be in line with the values of the religious right.

Offering that assurance is still a large part of what Pence does, but he has established a hugely influential role in the Senate.

While Pence has not yet surpassed the record for tie-breakers, he is on track to break some modern records for a vice president’s involvement in Senate votes.

The all-time record is held by John Adams, who cast 29 votes in the 1790s, followed closely by John C. Calhoun with 28 in the 1820s. In the 19th century, vice presidents were generally more active in the legislative branch, according to the Senate Historical Office:

The degree of influence and the role played within the Senate depended chiefly on the personality and inclinations of the individual involved. Some had great parliamentary skill and presided well, while others found the task boring, were incapable of maintaining order, or chose to spend most of their time away from Washington, leaving the duty to a president pro tempore. Some made an effort to preside fairly, while others used their position to promote the political agenda of the administration.

That’s largely changed. The vice president’s role is seen to be much closer to the executive branch — presiding over the Senate only ceremonially. For the most part that remains true for Pence, with a big exception: when he’s needed to break a tie.

This year, Pence was part of the Republican legislative strategy

In his final remarks of the year, Sen. Mitch McConnell admitted 2017 was a year of partisan politics.

“One thing I can say about this year was that it was pretty partisan,” McConnell said at his end-of-year press conference. “Most of the big things I mentioned were done mostly on largely a partisan basis.”

It was all part of the plan.

At the beginning of this year, with a 52-vote majority, far short of the 60 votes needed to overcome a filibuster, Republican leadership devised a plan to bypass Democrats altogether on major legislation: For their biggest agenda items — health care and tax reform — they would use “budget reconciliation,” which allows a bill that affects spending, revenue, or the debt ceiling to bypass the filibuster in the Senate.

It’s a process President Bill Clinton used to pass welfare reform in 1996 and President George W. Bush used to pass tax cuts in 2001 and 2003. It’s how President Barack Obama got several budgetary amendments to the Affordable Care Act passed.

It changed the dynamic of legislating. This year, Republicans only had to find consensus within their own ranks to repeal Obamacare or pass a tax cut, instead of bringing on at least eight Democrats — and they gave themselves a two-senator margin of error. If they lost two votes, Pence was always on hand to keep the agenda moving.

The strategy was successful with taxes, nominations, and reversing Obama-era rules. And while it failed on health care because three Republicans defected, with Sen. John McCain dealing the death blow, the tactic came close to success. Pence was on the Senate floor urging his Republican senators like McCain to keep in line.

In all, 2017 established an unprecedented way of legislating. Central to the strategy was Pence being on call.