The 114th Congress isn’t even a week old, and the V-word is already dominating the agenda as President Obama stacks up veto threats and Democratic leaders vow to deliver the votes to back him up.

Despite calls for cooperation from both sides and Republican efforts to line up bipartisan bills for their early agenda, Mr. Obama has issued veto threats on three measures. House Minority Leader Nancy Pelosi, California Democrat, said Thursday that her troops will vote to uphold those vetoes.

Meanwhile, Senate Democrats launched their first filibuster of the year on the third day of business — the fastest filibuster on record, according to an analysis.

The filibuster came on legislation to build the Keystone XL pipeline, which has bipartisan support. Indeed, six Democrats are co-sponsoring the bill, and along with the chamber’s 54 Republicans, that should be enough to overcome the filibuster early next week.

Still, Democrats refused to allow debate to begin without going through all of the procedural hoops, despite having criticized Republicans for that same practice when Republicans were in the minority last year.

“We’ll work through this because we’re determined to get bipartisan jobs legislation on the president’s desk as soon as we can,” said Senate Majority Leader Mitch McConnell, Kentucky Republican.

Mr. Obama has issued a veto threat on the Keystone measure. He also promised to veto a bill to repeal Obamacare’s 30-hour workweek definition and legislation that includes a two-year delay of Dodd-Frank financial reform regulations that require banks to segregate taxpayer-insured funds from money that the banks use for risky investments.

Sen. Joe Manchin III, West Virginia Democrat and a Keystone supporter, said Thursday he believes enough Democrats could rally behind the project for the Senate to override an Obama veto.

But Mrs. Pelosi said she will muster Democrats in her chamber to uphold the veto on Keystone and the other two issues where Mr. Obama has drawn lines.

She said Mr. Obama’s veto is the key to Democrats’ legislative strategy this year.

“Our leverage in the discussions springs from the fact that we have a Democrat in the White House where President Obama is signing or not signing a bill, and our upholding his veto strengthens the hand of the minority in a debate of this kind,” she said.

After years of blaming Republicans for blocking Democrats’ agenda, Mrs. Pelosi said that relying on the president to veto bills doesn’t make Democrats the “party of ‘No.’”

“We want a path to ‘Yes,’” she said. “We want to have an approach that has oneness, that has integrity, that is integral, that everything people see the relationship of, one thing to the other in the bill.”

Mrs. Pelosi led opposition Wednesday to the Dodd-Frank bill, helping switch dozens of Democrats who voted for a similar measure last year but opposed it this week. Thanks to those defections, the legislation failed to get the two-thirds vote needed to clear under expedited rules.

Mrs. Pelosi said she expects Republicans will bring the bill back under regular rules but Wednesday’s vote proves she can sustain an Obama veto on that, too.

Democrats’ reliance on the veto, and Mr. Obama’s eagerness to issue threats — he declared two bills dead Tuesday afternoon, just as Congress was officially opening — already has poisoned the atmosphere on Capitol Hill.

“At a minimum, he could have waited a few hours. Maybe he could have waited a few days,” said House Speaker John A. Boehner, Ohio Republican. “We were taking our oath of office when they were issuing veto threats. Come on.”

He said he expects to raise the issue of vetoes with Mr. Obama when the president hosts congressional leaders at the White House next week.

As Republicans blamed Democrats for blocking action, Democrats countered that Republicans were adopting tactics they fought when they were in the minority.

Adam Jentleson, spokesman for Senate Minority Leader Harry Reid, Nevada Democrat, accused Mr. McConnell of “bypassing the committee process” to bring the Keystone bill to the floor.

“We hope Republicans will rethink their approach in the coming weeks,” he said.

Republicans said they did send the bill through the Senate Energy and Natural Resources Committee, which approved it Thursday. They also said they wanted to have a hearing on the measure Wednesday, but Democrats used a parliamentary tactic to shut down the committee.

Mr. McConnell also offered the chance for Democrats and Republicans to offer amendments to the Keystone bill and asked for debate to begin Monday.

Democrats objected, forcing Mr. McConnell to go through the procedures of breaking a filibuster on the third day of the congressional session. That vote is likely to occur Monday.

It’s fastest a filibuster has ever been launched in the Senate, according to records dating back a century.

The previous record was a Republican filibuster at the beginning of the 111th Congress in 2009, which happened on the fourth day.

• S.A. Miller and Ben Wolfgang contributed to this report.

Sign up for Daily Newsletters Manage Newsletters

Copyright © 2020 The Washington Times, LLC. Click here for reprint permission.