By Deirdre Walsh

CNN Senior Congressional Producer

WASHINGTON (CNN) -- House GOP leaders, trying to shore up support for their health care bill, are giving conservatives a stark message: Are you with Nancy Pelosi or are you with President Donald Trump?

The No. 3 House Republican, Rep. Steve Scalise put up a slide at Wednesday morning's closed door Republican conference meeting that had a split screen, according to sources who attended the session. One slide had a picture of Pelosi, the House Democratic leader and former speaker, with a quote saying the Republican health care bill couldn't be any worse. On the other side was a picture of Trump with a quote saying he was proud to back the leadership's legislation.

Scalise referenced the picture, and according to these sources in the room, posed the question to members unhappy the bill doesn't go far enough to reverse Obamacare: whose side are you on?

House Speaker Paul Ryan downplayed conservative opposition to the Obamacare repeal and replace legislation rolled out earlier this week as "growing pains."

"I think what you're seeing is we're going through the inevitable growing pains of being an opposition party to becoming a governing party," Ryan told reporters Wednesday after a bloc of conservatives in the House Freedom Caucus sharply criticized the health care bill and suggested it didn't have the support to pass.

The speaker pointed out that roughly two-thirds of House GOP members "have never known what it's like to work with a Republican president and have unified government. So it's a new feel, it's a new system for people, but it's all the more reason why we have to do what we said we would do and deliver for the American people and govern, and use our principles."

Multiple GOP sources told CNN the meeting was a pep talk reminding members that they now had the opportunity to make good on a key campaign promise and they had a comprehensive plan to dismantle the health care law and the bill unveiled this week was a crucial first step.

The speaker ticked through a list of reasons he argued the current health care system is failing and the responsibility for congressional Republicans to fix it for the voters who elected them.

Pressed if he could produce a GOP majority to ensure the measure is approved, Ryan said, "I have no doubt we will pass this because we are going to keep our promises. Every House Republican, every, I think every Republican in Congress, including the President of the United States made a promise to the American people. And the promise we made to the American people is we are going to repeal and replace Obamacare."

White House, leaders working together

As the White House gears up its operation to sell the legislation the coordination between House GOP leadership and the White House and allies in the business and conservative community has ramped up.

Each morning at 8:45 a.m. ET, there is a conference call with staff from the House whip operation and leadership offices, the White House legislative office, and their supporters in the private sector to discuss the details on what's happening in the day ahead and what they envision as the message of the day, according to GOP congressional sources.

In addition, after the Obamacare repeal bill was introduced Monday night, a meeting was called with a variety of players representing interest groups and conservative organizations. Over 150 people showed up for the meeting Tuesday morning to get a briefing on the legislation and discuss the plan to continue reaching out to wavering members to get on board.

This story has been updated.