diff --git a/suave/builder/api/api.go b/suave/builder/api/api.go
index f144e65f18..773d7086af 100644
--- a/suave/builder/api/api.go
+++ b/suave/builder/api/api.go
@@ -16,8 +16,21 @@ type Bundle struct {
 	RefundPercent   *int               `json:"percent,omitempty"`
 }
 
+type BuildBlockArgs struct {
+	Slot           uint64
+	ProposerPubkey []byte
+	Parent         common.Hash
+	Timestamp      uint64
+	FeeRecipient   common.Address
+	GasLimit       uint64
+	Random         common.Hash
+	Withdrawals    []*types.Withdrawal
+	Extra          []byte
+	FillPending    bool
+}
+
 type API interface {
-	NewSession(ctx context.Context) (string, error)
+	NewSession(ctx context.Context, args *BuildBlockArgs) (string, error)
 	AddTransaction(ctx context.Context, sessionId string, tx *types.Transaction) (*types.SimulateTransactionResult, error)
 	AddBundle(ctx context.Context, sessionId string, bundle Bundle) error
 }
diff --git a/suave/builder/api/api_client.go b/suave/builder/api/api_client.go
index e7ca8246b4..62631df8b4 100644
--- a/suave/builder/api/api_client.go
+++ b/suave/builder/api/api_client.go
@@ -29,9 +29,9 @@ func NewClientFromRPC(rpc rpcClient) *APIClient {
 	return &APIClient{rpc: rpc}
 }
 
-func (a *APIClient) NewSession(ctx context.Context) (string, error) {
+func (a *APIClient) NewSession(ctx context.Context, args *BuildBlockArgs) (string, error) {
 	var id string
-	err := a.rpc.CallContext(ctx, &id, "suavex_newSession")
+	err := a.rpc.CallContext(ctx, &id, "suavex_newSession", args)
 	return id, err
 }
 
diff --git a/suave/builder/api/api_server.go b/suave/builder/api/api_server.go
index e78f435e14..eb598270d9 100644
--- a/suave/builder/api/api_server.go
+++ b/suave/builder/api/api_server.go
@@ -8,7 +8,7 @@ import (
 
 // SessionManager is the backend that manages the session state of the builder API.
 type SessionManager interface {
-	NewSession(context.Context) (string, error)
+	NewSession(context.Context, *BuildBlockArgs) (string, error)
 	AddTransaction(sessionId string, tx *types.Transaction) (*types.SimulateTransactionResult, error)
 	AddBundle(sessionId string, bundle Bundle) error
 }
@@ -24,8 +24,8 @@ type Server struct {
 	sessionMngr SessionManager
 }
 
-func (s *Server) NewSession(ctx context.Context) (string, error) {
-	return s.sessionMngr.NewSession(ctx)
+func (s *Server) NewSession(ctx context.Context, args *BuildBlockArgs) (string, error) {
+	return s.sessionMngr.NewSession(ctx, args)
 }
 
 func (s *Server) AddTransaction(ctx context.Context, sessionId string, tx *types.Transaction) (*types.SimulateTransactionResult, error) {
@@ -39,7 +39,7 @@ func (s *Server) AddBundle(ctx context.Context, sessionId string, bundle Bundle)
 type MockServer struct {
 }
 
-func (s *MockServer) NewSession(ctx context.Context) (string, error) {
+func (s *MockServer) NewSession(ctx context.Context, args *BuildBlockArgs) (string, error) {
 	return "", nil
 }
 
diff --git a/suave/builder/api/api_test.go b/suave/builder/api/api_test.go
index 30a9dabb39..356ff0d083 100644
--- a/suave/builder/api/api_test.go
+++ b/suave/builder/api/api_test.go
@@ -19,7 +19,7 @@ func TestAPI(t *testing.T) {
 
 	c := NewClientFromRPC(rpc.DialInProc(srv))
 
-	res0, err := c.NewSession(context.Background())
+	res0, err := c.NewSession(context.Background(), nil)
 	require.NoError(t, err)
 	require.Equal(t, res0, "1")
 
@@ -30,7 +30,7 @@ func TestAPI(t *testing.T) {
 
 type nullSessionManager struct{}
 
-func (nullSessionManager) NewSession(ctx context.Context) (string, error) {
+func (nullSessionManager) NewSession(ctx context.Context, args *BuildBlockArgs) (string, error) {
 	return "1", ctx.Err()
 }
 
diff --git a/suave/builder/session_manager.go b/suave/builder/session_manager.go
index 2a2ddda062..194bd9067d 100644
--- a/suave/builder/session_manager.go
+++ b/suave/builder/session_manager.go
@@ -74,7 +74,7 @@ func NewSessionManager(blockchain blockchain, config *Config) *SessionManager {
 }
 
 // NewSession creates a new builder session and returns the session id
-func (s *SessionManager) NewSession(ctx context.Context) (string, error) {
+func (s *SessionManager) NewSession(ctx context.Context, args *api.BuildBlockArgs) (string, error) {
 	// Wait for session to become available
 	select {
 	case <-s.sem:
diff --git a/suave/builder/session_manager_test.go b/suave/builder/session_manager_test.go
index a7a37aa14e..994c5e082f 100644
--- a/suave/builder/session_manager_test.go
+++ b/suave/builder/session_manager_test.go
@@ -22,7 +22,7 @@ func TestSessionManager_SessionTimeout(t *testing.T) {
 		SessionIdleTimeout: 500 * time.Millisecond,
 	})
 
-	id, err := mngr.NewSession(context.TODO())
+	id, err := mngr.NewSession(context.TODO(), nil)
 	require.NoError(t, err)
 
 	time.Sleep(1 * time.Second)
@@ -42,7 +42,7 @@ func TestSessionManager_MaxConcurrentSessions(t *testing.T) {
 	})
 
 	t.Run("SessionAvailable", func(t *testing.T) {
-		sess, err := mngr.NewSession(context.TODO())
+		sess, err := mngr.NewSession(context.TODO(), nil)
 		require.NoError(t, err)
 		require.NotZero(t, sess)
 	})
@@ -53,7 +53,7 @@ func TestSessionManager_MaxConcurrentSessions(t *testing.T) {
 		ctx, cancel := context.WithCancel(context.Background())
 		cancel()
 
-		sess, err := mngr.NewSession(ctx)
+		sess, err := mngr.NewSession(ctx, nil)
 		require.Zero(t, sess)
 		require.ErrorIs(t, err, context.Canceled)
 	})
@@ -62,7 +62,7 @@ func TestSessionManager_MaxConcurrentSessions(t *testing.T) {
 		time.Sleep(d) // Wait for the session to expire.
 
 		// We should be able to open a session again.
-		sess, err := mngr.NewSession(context.TODO())
+		sess, err := mngr.NewSession(context.TODO(), nil)
 		require.NoError(t, err)
 		require.NotZero(t, sess)
 	})
@@ -73,7 +73,7 @@ func TestSessionManager_SessionRefresh(t *testing.T) {
 		SessionIdleTimeout: 500 * time.Millisecond,
 	})
 
-	id, err := mngr.NewSession(context.TODO())
+	id, err := mngr.NewSession(context.TODO(), nil)
 	require.NoError(t, err)
 
 	// if we query the session under the idle timeout,
@@ -98,7 +98,7 @@ func TestSessionManager_StartSession(t *testing.T) {
 	// test that the session starts and it can simulate transactions
 	mngr, bMock := newSessionManager(t, &Config{})
 
-	id, err := mngr.NewSession(context.TODO())
+	id, err := mngr.NewSession(context.TODO(), nil)
 	require.NoError(t, err)
 
 	txn := bMock.state.newTransfer(t, common.Address{}, big.NewInt(1))